i386: Compile rtld-*.os with -mno-sse -mno-mmx -mfpmath=387
Compile i386 rtld-*.os with -mno-sse -mno-mmx -mfpmath=387 so that no
code in ld.so uses mm/xmm/ymm/zmm registers on i386 since the first 3
mm/xmm/ymm/zmm registers are used to pass vector parameters which must
be preserved.