Move powerpc llround implementations to powerpc32 directory.

sysdeps/powerpc/fpu/ has versions of llround and llroundf that are
actually used only for powerpc32 because
sysdeps/powerpc/powerpc64/fpu/ has its own versions of those
functions.  This patch moves them into sysdeps/powerpc/powerpc32/fpu
to reflect where they are actually used (in preparation for fixing
other problems with those functions).

Tested for powerpc that installed stripped shared libraries are
unchanged by this patch.

	* sysdeps/powerpc/fpu/s_llround.c: Move to ....
	* sysdeps/powerpc/powerpc32/fpu/s_llround.c: ...here.
	* sysdeps/powerpc/fpu/s_llroundf.c: Move to ....
	* sysdeps/powerpc/powerpc32/fpu/s_llroundf.c: ...here.