Use libm_alias_* in soft-fp.

Use libm_alias_* in soft-fp.

This patch makes the soft-fp implementations of fma functions use the
libm_alias_* macros.

Tested with build-many-glibcs.py that installed stripped shared
libraries are unchanged by the patch.

	* soft-fp/fmadf4.c: Include <libm-alias-double.h>.
	[!__fma] (fma): Define using libm_alias_double.
	* soft-fp/fmasf4.c: Include <libm-alias-float.h>.
	[!__fmaf] (fmaf): Define using libm_alias_float.
	* soft-fp/fmatf4.c: Include <libm-alias-ldouble.h>.
	(fmal): Define using libm_alias_ldouble.