Turn on -Werror=implicit-function-declaration

GCC 4.4, the minimum compiler version, supports this option.  Unlike
other warnings, -Wimplicit-function-declaration warnings should be
independent of compiler versions, so this change should not cause
compiler-specific build failures.
PowerPC: multiarch bzero cleanup for PPC64

This patch cleanups the multiarch bzero for powerpc64 by remove
the multiarch objects and use instead the the memset embedded
implementation presented in each multiarch optimization.  The
code generate is essentially the same, but the TB_TOCLESS (which
is not essential).
PowerPC: memset optimization for POWER8/PPC64

This patch adds an optimized memset implementation for POWER8.  For
sizes from 0 to 255 bytes, a word/doubleword algorithm similar to
POWER7 optimized one is used.

For size higher than 255 two strategies are used:

1. If the constant is different than 0, the memory is written with
   altivec vector instruction;

2. If constant is 0, dbcz instructions are used.  The loop is unrolled
   to clear 512 byte at time.

Using vector instructions increases throughput considerable, with a
double performance for sizes larger than 1024.  The dcbz loops unrolls
also shows performance improvement, by doubling throughput for sizes
larger than 8192 bytes.
Return failure in getnetgrent only when all netgroups have been searched (#17363)

The netgroups lookup code fails when one of the groups in the search
tree is empty.  In such a case it only returns the leaves of the tree
after the blank netgroup.  This is because the line parser returns a
NOTFOUND status when the netgroup exists but is empty.  The
__getnetgrent_internal implementation needs to be fixed to try
remaining groups if the current group is entry.  This patch implements
this fix.  Tested on x86_64.

	[BZ #17363]
	* inet/getnetgrent_r.c (__internal_getnetgrent_r): Try next
	group if the current group is empty.
tile: remove linux lowlevellock.h