* acinclude.m4 (GLIBCXX_EXPORT_INCLUDES):  Remove LIBMATH_INCLUDES
	and LIBSUPCXX_INCLUDES.  Re-purpose TOPLEVEL_INCLUDES to refer to
	things from the top level.
	* configure.ac (GLIBCXX_IS_NATIVE):  Determine earlier and re-order.
	Comment out the conditionals for CANADIAN and GLIBCXX_BUILD_LIBMATH
	(currently unused).  Strip the fake-VPATH shell fragment from
	automake-generated rules, if present.
	* linkage.m4:  Add comment.

	* fragment.am:  New file, containing factored-out common settings.
	(AM_CPPFLAGS):  Absorb the deprecated INCLUDES variable contents.
	* Makefile.am:  Include fragment.am.  Remove common variables.
	* include/Makefile.am:  Likewise.
	* libmath/Makefile.am:  Likewise.
	* libsupc++/Makefile.am:  Likewise.
	* po/Makefile.am:  Likewise.  Print rules during check.
	* src/Makefile.am:  Likewise.
	* testsuite/Makefile.am:  Likewise.

	* aclocal.m4, configure, Makefile.in, include/Makefile.in,
	libmath/Makefile.in, libsupc++/Makefile.in, po/Makefile.in,
	src/Makefile.in, testsuite/Makefile.in:  Regenerate.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@70522 138bc75d-0d04-0410-961f-82ee72b054a4