gthr.m4: New.

gthr.m4: New.

	    * config/gthr.m4: New. Define GCC_AC_THREAD_HEADER.
	    * libgcc/configure: Regenerate.
	    * libgcc/configure.ac: Replace code with GCC_AC_THREAD_HEADER use.
	    * libstdc++-v3/Makefile.in: Regenerate.
	    * libstdc++-v3/acinclude.m4: Replace code with GCC_AC_THREAD_HEADER use.
	    * libstdc++-v3/configure: Regenerate.
	    * libstdc++-v3/doc/Makefile.in: Regenerate.
	    * libstdc++-v3/include/Makefile.am: Regenerate.
	    * libstdc++-v3/include/Makefile.in: Rename variable.
	    * libstdc++-v3/libsupc++/Makefile.in: Regenerate.
	    * libstdc++-v3/po/Makefile.in: Regenerate.
	    * libstdc++-v3/python/Makefile.in: Regenerate.
	    * libstdc++-v3/src/Makefile.in: Regenerate.
	    * libstdc++-v3/src/c++11/Makefile.in: Regenerate.
	    * libstdc++-v3/src/c++98/Makefile.in: Regenerate.
	    * libstdc++-v3/testsuite/Makefile.in: Regenerate.

From-SVN: r192458