PowerPC: ifunc improvement for internal calls

This patch changes de default symbol redirection for internal call of
memcpy, memset, memchr, and strlen to the IFUNC resolved ones.  The
performance improvement is noticeable in algorithms that uses these
symbols extensible, like the regex functions.
Fix -Wundef issues in generated errlist.c.
Move rules for Linux-specific pldd program to Linux-specific Makefile.