configure.ac: Move pthread affinity test to the place where '-pthread' passed to...

configure.ac: Move pthread affinity test to the place where '-pthread' passed to CFLAGS.

libcilkrts/
	* configure.ac: Move pthread affinity test to the place where
	'-pthread' passed to CFLAGS. Otherwise the test always fails.
	(XCFLAGS): New variable for correctly passing
	'-pthread'.
	(XLDFLAGS): New variable for passing the correct pthread lib.
	* configure: Regenerate.
	* Makefile.am (AM_CFLAGS): Add $XCFLAGS.
	(AM_LDFLAGS): Add $XLDFLAGS.
	* Makefile.in: Regenerate.

From-SVN: r213854