In r260015, I renamed several identifiers to avoid -Wsystem-header
warnings.  In r261283, I imported libc++ 3.4 release, but this contained
one identifier that had not been renamed yet, leading to a compilation
error when using -std=c++1y.  Fix the compilation error by correctly
renaming the identifier.

Reported by:	rcarter@pinyon.org
PR:		base/192139
MFC after:	3 days
Fix arm build breakage when building stable/10 on
head/.

MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Also export UNAME_r to fix arm builds.

MFC after:	3 days
X-MFC-with:	r270417
Sponsored by:	The FreeBSD Foundation