at least mips support is broken, but microblazed and possibly other
archs work.
while building mips the following error was encountered:
Mode = sf\|df
Suffix = si\|2\|3
/tmp/musl-cross-make/gcc-4.9.3/build0/./gcc/xgcc -B/tmp/musl-cross-make/gcc-4.9.3/build0/./gcc/ -B/tmp/musl-cross-make/output/mips-linux-musl/bin/ -B/tmp/musl-cross-make/output/mips-linux-musl/lib/ -isystem /tmp/musl-cross-make/output/mips-linux-musl/include -isystem /tmp/musl-cross-make/output/mips-linux-musl/sys-include -g -O2 -O0 -g0 -minterlink-mips16 -O2 -g -O2 -O0 -g0 -minterlink-mips16 -DIN_GCC -DCROSS_DIRECTORY_STRUCTURE -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -isystem ./include -fPIC -g -DIN_LIBGCC2 -fbuilding-libgcc -fno-stack-protector -Dinhibit_libc -fPIC -I. -I. -I../.././gcc -I../../../libgcc -I../../../libgcc/. -I../../../libgcc/../gcc -I../../../libgcc/../include -DHAVE_CC_TLS -o subsf3.o -MT subsf3.o -MD -MP -MF subsf3.dep subsf3 -c ../../../libgcc/config/hardfp.c -fvisibility=hidden -DHIDE_EXPORTS -Wno-missing-prototypes
xgcc: error: subsf3: No such file or directory
make[3]: *** [subsf3.o] Error 1
this seems like a bug in a shell command that's invoked during the build,
possibly a sed command using GNU-only syntax.
