PR libstdc++/38092
	* acinclude.m4 (HAVE_AS_SYMVER_DIRECTIVE): New test.
	* src/compatibility.cc: Don't use .symver directives if
	_GLIBCXX_HAVE_AS_SYMVER_DIRECTIVE is not defined.
	* config.h.in: Regenerated.
	* configure: Likewise.

From-SVN: r143169