re PR libstdc++/56475 (Incorrect result of configure test for /dev/random (_GLIBCXX_USE_RANDOM_TR1) for MinGW platform (and others?))

	PR libstdc++/56475
	* acinclude.m4 (GLIBCXX_CHECK_RANDOM_TR1): Disable check for
	mingw-targets.
	* configure: Regenerated.

From-SVN: r196371