Use libm_alias_double for powerpc fabs, fma.

Use libm_alias_double for powerpc fabs, fma.

Continuing the preparation for additional _FloatN / _FloatNx function
aliases, this patch makes powerpc fabs and fma use libm_alias_double
to define function aliases.  This brings in automatic symbol
versioning compat handling, so the powerpc32 and powerpc64 wrappers
that added such handling to the generic sysdeps/powerpc/fpu versions
are removed as no longer required (there are no sysdeps directory
ordering issues that would necessitate keeping trivial wrappers
there).

Tested with build-many-glibcs.py that installed stripped shared
libraries are unchanged for all its hard-float powerpc configurations.

	* sysdeps/powerpc/fpu/s_fabs.S: Include <libm-alias-double.h>.
	(fabs): Define using libm_alias_double.
	* sysdeps/powerpc/fpu/s_fma.S: Include <libm-alias-double.h>.
	(fma): Define using libm_alias_double.
	* sysdeps/powerpc/powerpc32/fpu/s_fabs.S: Remove file.
	* sysdeps/powerpc/powerpc32/fpu/s_fma.S: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_fabs.S: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_fma.S: Likewise.