Building opal on a Mac fails with "clang: error: unknown argument: '-m486'"

[cmacordex]

I successfully built ptlib on my Mac OS X 10.11.6 system with only one small issue (I will make a PR for that on the ptlib repository soon), but when building opal I get this error message:

[CC] src/codec/speex/libspeex/fftwrap.c
[AR] lib_Darwin_x86_64/libopal_s.a
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool: file: /Users/.../source/opaltemp/lib_Darwin_x86_64/obj/guid.o has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool: file: /Users/.../source/opaltemp/lib_Darwin_x86_64/obj/mcs.o has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool: file: /Users/.../source/opaltemp/lib_Darwin_x86_64/obj/gcc.o has no symbols
[LD] lib_Darwin_x86_64/libopal.3.10.15.dylib
rm -f /Users/.../source/opaltemp/lib_Darwin_x86_64/libopal.dylib ; ln -sf  libopal.3.10.15.dylib /Users/.../source/opaltemp/lib_Darwin_x86_64/libopal.dylib
[CC] gsm06_10_codec.c
clang: error: unknown argument: '-m486'
make[3]: *** [/Users/.../source/opaltemp/plugins/../lib_Darwin_x86_64/plugins/gsm0610/gsm06_10_codec.o] Error 1
make[2]: *** [all] Error 2
make[1]: *** [subdirs] Error 2
make: *** [opt] Error 2

I wasn't able to find "m486" in the opal repository anywhere though, so I don't know if it's something that can be fixed within opal.

UPDATE: I thought perhaps it might work with gcc but not with clang, so I used homebrew to install gcc and run that instead, but unfortunately I get nearly the same error:

PATH="/usr/local/bin:$PATH" make
/Library/Developer/CommandLineTools/usr/bin/make DEBUG_BUILD=no OPAL_SHARED_LIB=1
[CC] gsm06_10_codec.c
gcc: error: unrecognized command line option '-m486'; did you mean '-m16'?
make[3]: *** [/Users/.../source/opaltemp/plugins/../lib_Darwin_x86_64/plugins/gsm0610/gsm06_10_codec.o] Error 1
make[2]: *** [all] Error 2
make[1]: *** [subdirs] Error 2
make: *** [opt] Error 2