OpenWrt is not self-hosting, you need to use its buildroot for cross-compiling on another general purpose distribution (Arch, Debian, Fedora, Gentoo, OpenSuSE, Ubuntu, ...), even on x86.
Hopefully it will show up in make menuconfig -- if it doesn't try removing the OpenWrt ./tmp/ directory and its contents. (That is not your build system's /tmp/ , though that shouldn't kill you if you make that mistake.) Build to make sure it is "clean"
RM /tmp
then "make menuconfig" showing following:
Warning: make file 'package/feeds/shadowsocksr-libev/makefile' has a build dependency on 'libmbedltls' and 'libpcre', which does not exist
If not a typo, you removed /tmp/, not the tmp/ in your OpenWrt build root. Thankfully (and I've done it myself a few times), there usually isn't anything system-critical in /tmp/
Running, in the OpenWrt build root, on your build machine
./scripts/feeds update -a
./scripts/feeds install -a
OK, I'm seeing the same error -- by using the </> button, you can format text, like copied error messages, for easy reading -- I assumed the l was a typo in transcription
jeff@deb-devel:~/devel/openwrt-ssd$ ./scripts/feeds install -a
Collecting package info: done
WARNING: Makefile 'package/feeds/shadowsocksr-libev/Makefile' has a build dependency on 'libmbedltls', which does not exist
WARNING: Makefile 'package/feeds/shadowsocksr-libev/Makefile' has a build dependency on 'libpcre', which does not exist
Installing all packages from feed packages.
Installing all packages from feed luci.
Installing all packages from feed routing.
Installing all packages from feed telephony.
I selected shadowsocks-libev-ss-server in make menuconfig
What I have to say it that, the ShadowsocksR server mentioned above requires a patched version of libmbedtls, and by default it builds a stand-alone libmbedtls package, which is further conflict with the Shadowsocks's libmbedtls package.