Disable -std=c99 on linux for now, as gcc does freaks out in math_private.h
on the definition of IEEE_WORD_ORDER, and defines ieee_double_shape_type twice.
Disable building s_cbrtl.c for the time being as it requires ieeefp.h
A couple of small issues still remain with linking:
LINK all
/usr/bin/ranlib: file: libopenlibm.a(e_rem_pio2.o) has no symbols
/usr/bin/ranlib: file: libopenlibm.a(e_rem_pio2f.o) has no symbols
/usr/bin/ranlib: file: libopenlibm.a(k_cosf.o) has no symbols
/usr/bin/ranlib: file: libopenlibm.a(k_sinf.o) has no symbols
/usr/bin/ranlib: file: libopenlibm.a(k_tanf.o) has no symbols
LINK all
ld: duplicate symbol ___ieee754_rem_pio2 in src/s_sin.o and src/s_cos.o for architecture x86_64
collect2: ld returned 1 exit status