bug#9492: cannot override CC when using system copy of libtool ("The wrong-gcc problem")

[Maxim Cournoyer]

Hello,

Just a heads-up that this old bug is still relevant.  It means that one
cannot use libtool stand-alone (without Autotools) and expect
cross-compilation or even just switching temporarily compilers
(e.g. from 'gcc' to 'clang' via CC to test something).  Heres' what the
failure look like:

--8<---------------cut here---------------start------------->8---
libtool: link: gcc -shared  -fPIC -DPIC  build/obj/Core/.libs/apu.c.o 
build/obj/Core/.libs/camera.c.o build/obj/Core/.libs/cheats.c.o 
build/obj/Core/.libs/debugger.c.o build/obj/Core/.libs/display.c.o 
build/obj/Core/.libs/gb.c.o build/obj/Core/.libs/joypad.c.o 
build/obj/Core/.libs/mbc.c.o build/obj/Core/.libs/memory.c.o 
build/obj/Core/.libs/printer.c.o build/obj/Core/.libs/random.c.o 
build/obj/Core/.libs/rewind.c.o build/obj/Core/.libs/rumble.c.o 
build/obj/Core/.libs/save_state.c.o build/obj/Core/.libs/sgb.c.o 
build/obj/Core/.libs/sm83_cpu.c.o build/obj/Core/.libs/sm83_disassembler.c.o 
build/obj/Core/.libs/symbol_hash.c.o build/obj/Core/.libs/timing.c.o 
build/obj/Core/.libs/workboy.c.o      -Wl,-soname -Wl,libsameboy.so.0 -o 
build/lib/.libs/libsameboy.so.0.0.0
/gnu/store/gpq3h81bzjpirwnc0fzwsph788b9rwn4-libtool-2.5.3/bin/libtool: line 
10778: gcc: command not found
make: *** [Makefile:832: build/lib/libsameboy.la] Error 127
make: *** Waiting for unfinished jobs....
error: in phase 'build': uncaught exception:
--8<---------------cut here---------------end--------------->8---


That's when building some Make-based software that calls libtool
directly.  Here, the libtool version was built with GCC (has baked
CC="gcc" variable around line 326), which is what it uses when linking
with its $archive_cmds variable defined a bit later (line 368):

--8<---------------cut here---------------start------------->8---
archive_cmds="\$CC -shared \$pic_flag \$libobjs \$deplibs \$compiler_flags 
\$wl-soname \$wl\$soname -o \$lib"
--8<---------------cut here---------------end--------------->8---

Seems this should be able to fix?  Check for environment CC, if not set,
defaults to gcc?  Would this simple fix be enough?

-- 
Thanks,
Maxim