Build for D-Link DSL-2750B D1 fails: gdb variable undeclared

Compiling on debian stretch x86, following the exact steps included in pages https://openwrt.org/docs/guide-developer/build-system/install-buildsystem
https://openwrt.org/docs/guide-developer/build-system/use-buildsystem#make_menuconfig
All required deps are installed, feeds updated and installed, correct seed imported and checked out against last stable release (which currently is 19.07.2)
make -r world -j1 V=s fails with error:

make[7]: Leaving directory '/home/user/openwrt/build_dir/toolchain-mips_mips32_gcc-7.5.0_musl/gdb-8.3.1/gdb'
g++ -x c++  -g -O2   -I. -I. -I./config -DLOCALEDIR="\"/home/user/openwrt/staging_dir/toolchain-mips_mips32_gcc-7.5.0_musl/share/locale\"" -DHAVE_CONFIG_H -I./../include/opcode -I./../readline/.. -I./../zlib -I../bfd -I./../bfd -I./../include -I../libdecnumber -I./../libdecnumber  -I./gnulib/import -Ibuild-gnulib/import  -DTUI=1 -I/home/user/openwrt/staging_dir/host/include     -Wall -Wpointer-arith -Wno-unused -Wunused-value -Wunused-variable -Wunused-function -Wno-switch -Wno-char-subscripts -Wempty-body -Wunused-but-set-parameter -Wunused-but-set-variable -Wno-sign-compare -Wno-error=maybe-uninitialized -Wsuggest-override -Wduplicated-cond -Wformat -Wformat-nonliteral  -c -o auto-load.o -MT auto-load.o -MMD -MP -MF ./.deps/auto-load.Tpo auto-load.c
auto-load.c: In function 'void set_auto_load_dir(const char*, int, cmd_list_element*)':
auto-load.c:149:32: error: 'AUTO_LOAD_DIR' was not declared in this scope
       auto_load_dir = xstrdup (AUTO_LOAD_DIR);
                                ^~~~~~~~~~~~~
auto-load.c: In function 'void set_auto_load_safe_path(const char*, int, cmd_list_element*)':
auto-load.c:265:38: error: 'AUTO_LOAD_SAFE_PATH' was not declared in this scope
       auto_load_safe_path = xstrdup (AUTO_LOAD_SAFE_PATH);
                                      ^~~~~~~~~~~~~~~~~~~
auto-load.c: In function 'void _initialize_auto_load()':
auto-load.c:1582:28: error: 'AUTO_LOAD_DIR' was not declared in this scope
   auto_load_dir = xstrdup (AUTO_LOAD_DIR);
                            ^~~~~~~~~~~~~
auto-load.c:1635:34: error: 'AUTO_LOAD_SAFE_PATH' was not declared in this scope
   auto_load_safe_path = xstrdup (AUTO_LOAD_SAFE_PATH);
                                  ^~~~~~~~~~~~~~~~~~~

I have no idea of the reason behind this, since in gdb/config.h the variable is declared:

#define AUTO_LOAD_DIR "$debugdir:$datadir/auto-load"

i have met the same problem.i try unsetting C_INCLUDE_PATH and CPLUS_INCLUDE_PLUS varible. then i pass the error.