powerpc: copysign cleanup

GCC always expand copysign{f} for all possible cpus, so calling the libm
is only done if user explicitly states to disable the builtin (which is
done usually not for performance reason).  So to provide ifunc variant
for copysign is just unrequired complexity, since libm will be called
on non-performance critical code.

This patch removes both powerpc32 and powerpc64 ifunc variants and
consolidates the powerpc implementation on
sysdeps/powerpc/fpu/s_copysign{f}.c using compiler builtins.

Checked on powerpc-linux-gnu (built without --with-cpu, with
--with-cpu=power4 and with --with-cpu=power5+ and --disable-multi-arch),
powerpc64-linux-gnu (built without --with-cp and with --with-cpu=power5+
and --disable-multi-arch).

	* sysdeps/powerpc/fpu/s_copysign.c: New file.
	* sysdeps/powerpc/fpu/s_copysignf.c: Likewise.
	* sysdeps/powerpc/powerpc32/fpu/s_copysign.S: Remove file.
	* sysdeps/powerpc/powerpc32/fpu/s_copysignf.S: Likewise.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/Makefile
	(sysdep_routines, libm-sysdep_routines): Remove s_copysign-power6 and
	s_copysign-ppc32.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_copysign-power6.S:
	Remove file.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_copysign-ppc32.S:
	Likewise.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_copysign.c:
	Likewise.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_copysignf.c:
	Likewise.
	* sysdeps/powerpc/powerpc32/power6/fpu/s_copysign.S: Likewise.
	* sysdeps/powerpc/powerpc32/power6/fpu/s_copysignf.S: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/Makefile (sysdeps_calls):
	Remove s_copysign-power6 s_copysign-ppc64.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_copysign-power6.S:
	Remove file.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_copysign-ppc64.S:
	Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_copysign.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_copysignf.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_copysign.S: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_copysignf.S: Likewise.
	* sysdeps/powerpc/powerpc64/power6/fpu/s_copysign.S: Likewise.
	* sysdeps/powerpc/powerpc64/power6/fpu/s_copysignf.S: Likewise.

Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>