Packaging "Dit" error: cannot find install-sh, install.sh, or shtool

I am trying to package the text editor Dit (code here). I am not very good with GNU Autotools, but it seems like a fairly standard Autotools setup to me.

Unfortunately I keep encountering this build error in my 18.06 buildroot (currently configured for mipsel_24kc_musl) on a Ubuntu 20.04.5 host:

autoreconf: Entering directory `.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: /home/jason/Code/openwrt/staging_dir/host/bin/aclocal -I /home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/host/share/aclocal -I /home/jason/Code/openwrt/staging_dir/hostpkg/share/aclocal -I /home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/usr/share/aclocal -I m4 -I . --force 
autoreconf: configure.ac: tracing
autoreconf: configure.ac: not using Libtool
autoreconf: running: /home/jason/Code/openwrt/staging_dir/host/bin/autoconf --include=/home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/host/share/aclocal --include=/home/jason/Code/openwrt/staging_dir/hostpkg/share/aclocal --include=/home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/usr/share/aclocal --include=m4 --include=. --prepend-include=/home/jason/Code/openwrt/staging_dir/host/share/aclocal --force
configure.ac:44: error: possibly undefined macro: AC_MSG_ERROR
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
autoreconf: /home/jason/Code/openwrt/staging_dir/host/bin/autoconf failed with exit status: 1
(cd /home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7/./; if [ -x ./configure ]; then find /home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7/ -name config.guess | xargs -r chmod u+w; find /home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7/ -name config.guess | xargs -r -n1 cp --remove-destination /home/jason/Code/openwrt/scripts/config.guess; find /home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7/ -name config.sub | xargs -r chmod u+w; find /home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7/ -name config.sub | xargs -r -n1 cp --remove-destination /home/jason/Code/openwrt/scripts/config.sub; AR="mipsel-openwrt-linux-musl-gcc-ar" AS="mipsel-openwrt-linux-musl-gcc -c -Os -pipe -mno-branch-likely -mips32r2 -mtune=24kc -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -msoft-float -iremap/home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7:dit-0.7 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro" LD=mipsel-openwrt-linux-musl-ld NM="mipsel-openwrt-linux-musl-gcc-nm" CC="mipsel-openwrt-linux-musl-gcc" GCC="mipsel-openwrt-linux-musl-gcc" CXX="mipsel-openwrt-linux-musl-g++" RANLIB="mipsel-openwrt-linux-musl-gcc-ranlib" STRIP=mipsel-openwrt-linux-musl-strip OBJCOPY=mipsel-openwrt-linux-musl-objcopy OBJDUMP=mipsel-openwrt-linux-musl-objdump SIZE=mipsel-openwrt-linux-musl-size CFLAGS="-Os -pipe -mno-branch-likely -mips32r2 -mtune=24kc -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -msoft-float -mips16 -minterlink-mips16 -iremap/home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7:dit-0.7 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro " CXXFLAGS="-Os -pipe -mno-branch-likely -mips32r2 -mtune=24kc -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -msoft-float -mips16 -minterlink-mips16 -iremap/home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7:dit-0.7 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro " CPPFLAGS="-I/home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/usr/include -I/home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/include -I/home/jason/Code/openwrt/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/usr/include -I/home/jason/Code/openwrt/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/include/fortify -I/home/jason/Code/openwrt/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/include " LDFLAGS="-L/home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/usr/lib -L/home/jason/Code/openwrt/staging_dir/target-mipsel_24kc_musl/lib -L/home/jason/Code/openwrt/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/usr/lib -L/home/jason/Code/openwrt/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/lib -znow -zrelro "   ./configure --target=mipsel-openwrt-linux --host=mipsel-openwrt-linux --build=x86_64-pc-linux-gnu --program-prefix="" --program-suffix="" --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --libexecdir=/usr/lib --sysconfdir=/etc --datadir=/usr/share --localstatedir=/var --mandir=/usr/man --infodir=/usr/info --disable-nls  ; fi; )
configure: WARNING: unrecognized options: --disable-nls
configure: loading site script /home/jason/Code/openwrt/include/site/mipsel
configure: error: cannot find install-sh, install.sh, or shtool in "." "./.." "./../.."
make[2]: *** [Makefile:47: /home/jason/Code/openwrt/build_dir/target-mipsel_24kc_musl/dit-0.7/.configured_68b329da9893e34099c7d8ad5cb9c940] Error 1

Most search results I've found point the finger at some part of autotools or libtoolize not being installed. However, I'm pretty sure I've got all the ones I need (and probably then some):

PKG_BUILD_DEPENDS:=bash libtool automake autoconf libtool-bin

The above error happens with PKG_FIXUP:=autoreconf in the Makefile; without it I get a different error:

make[3]: *** No targets specified and no makefile found.  Stop.

...which, from the wiki, seems like the problem PKG_FIXUP:=autoreconf was intended to solve.

Here's the current (incomplete) Makefile:

include $(TOPDIR)/rules.mk

PKG_NAME:=dit
PKG_VERSION:=0.7
PKG_RELEASE:=1

PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
PKG_SOURCE_PROTO:=git
PKG_SOURCE_URL:=https://github.com/hishamhm/dit.git
PKG_SOURCE_VERSION:=1ea5a13ae5987145363c121347c8b2c173d4c281
PKG_HASH:=skip

PKG_BUILD_DEPENDS:=bash libtool automake autoconf libtool-bin

# PKG_FIXUP:=autoreconf
PKG_INSTALL:=1
# PKG_BUILD_PARALLEL:=1

include $(INCLUDE_DIR)/package.mk

define Package/dit
    SUBMENU:=Editors
    SECTION:=utils
    CATEGORY:=Utilities
    TITLE:=A console text editor for Unix systems that you already know how to use.
    URL:=http://hisham.hm/dit/
    DEPENDS:=
endef

define Package/dit/description
    Dit is a text editor that uses modern shortcut keys and idioms for editing.
endef

# CONFIGURE_ARGS+=--enable-bundled-lua=no

define Package/dit/install
    $(INSTALL_DIR) $(1)/usr/bin
    $(CP) $(PKG_INSTALL_DIR)/usr/bin/$(PKG_NAME) $(1)/usr/bin/
endef

$(eval $(call BuildPackage,dit))

I'm at a loss for what the issue is here, or whether it's simple or complicated. Is anyone familiar enough with autotools packaging that they see the problem?