This patch cleanup some multiarch code related to memmmove
optimization. Initial IFUNC support added specialized wordcopy
symbols which turned in local IFUNC calls used by memmove default
implementation. The patch removes the internal IFUNC for wordcopy
symbols and uses local branches in the memmmove optimization instead.
Now that MEMCPY_OK_FOR_FWD_MEMMOVE should be define on memcopy.h there
is no need to specialized powerpc memmove implementation. This patch
moves the define set to powerpc memcopy and cleanup its definition on
powerpc code.
