MFC r282115, r282152, r282201

MFC	r282115, r282152, r282201
MFV	r282150
libgomp: Update to version 4.3.5.
bring initial BSD support from upstream.

This was not meant to be MFC'd at first but the original OMP support
for FreeBSD was in very poor shape.  The effect of this change should
be minimal as all ports are already using the version of libgomp that
comes with the gcc ports. The local libgomp is planned to be disabled
for platforms that are not using older gcc by default so this version
of libgomp will not be shipped in tier-1 platform releases.

Discussed with:	emaste

git-svn-id: svn://svn.freebsd.org/base/stable/10@283010 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f