MFC r258826, r259555, r 259558:

MFC	r258826, r259555, r 259558:

libcpp: Merge fixes from upstream
Fixes:
GCC preprocessor/29966:
GCC preprocessor/28709:
GCC c/31924
GCC preprocessor/14331

gcc: add Apple-compatible -Wnewline-eof

Obtained from:	gcc per-4.3 (rev. 121340, 124356, 124358, 124730,
				  125212, 125255 ; GPLv2)
		Apple Inc. (Apple GCC 4.2 - 5531)

git-svn-id: svn://svn.freebsd.org/base/stable/10@259890 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f