PowerPC: initial support for multilib for PowerPC32

This patch add a empty Makefile, the C IFUNC helper macros, and a empty
available IFUNC implementation enumeration.
PowerPC: multiarch memcpy for PowerPC32
PowerPC: multiarch memcmp for PowerPC32
PowerPC: multiarch memset/bzero for PowerPC32
PowerPC: multiarch mempcpy for PowerPC32
PowerPC: multiarch memchr for PowerPC32
PowerPC: multiarch memrchr for PowerPC32
PowerPC: multiarch rawmemchr for PowerPC32
PowerPC: multiarch strlen for PowerPC32
PowerPC: multiarch strnlen for PowerPC32
PowerPC: multiarch strncmp for PowerPC32
PowerPC: multiarch strcasecmp for PowerPC32
PowerPC: multiarch strncasecmp for PowerPC32
PowerPC: multiarch strchrnul for PowerPC32
PowerPC: multiarch strchr for PowerPC32
PowerPC: multiarch wcschr for PowerPC32
PowerPC: multiarch wcsrchr for PowerPC32
PowerPC: multiarch wcscpy for PowerPC32
PowerPC: multiarch wordcopy routines for PowerPC32
PowerPC: change sysdeps fpu folder

This patch makes the fpu/multiarch folder appears in front of the
powerpc/fpu folder.