PR libstdc++/84773
	PR libstdc++/83662
	* crossconfig.m4: Check for aligned_alloc etc. on freebsd and mingw32.
	* configure: Regenerate.
	* include/c_global/cstdlib [_GLIBCXX_HAVE_ALIGNED_ALLOC]
	(aligned_alloc): Add using-declaration.
	* testsuite/18_support/aligned_alloc/aligned_alloc.cc: New test.

From-SVN: r258468