* libc/include/ieeefp.h: use prefixed __ieeefp_ macros that can be
overridden via machine/ieeefp.h.
* libc/include/machine/ieeefp.h: Add SPU specific C99 and ieeefp
macros for isnan and related macros.
* libc/include/math.h: Allow C99 isfinite, isinf, and isnan to be
overridden via machine/ieeefp.h.
* libm/machine/spu/Makefile.am: Add new files.
* libm/machine/spu/Makefile.in: Autogenerate with new files.
* libm/machine/spu/sf_fpclassify.c: Add SPU specific __fpclassifyf.
* libm/machine/spu/sf_finite.c: Add SPU specific finitef.
* libm/machine/spu/sf_isinf.c: Add SPU specific isinff.
* libm/machine/spu/sf_isinff.c: Add SPU specific __isinff.
* libm/machine/spu/sf_isnan.c: Add SPU specific isnanf.
* libm/machine/spu/sf_isnanf.c: Add SPU specific __isnanf.
* libm/machine/spu/sf_nan.c: Add SPU specific nanf.