re PR libstdc++/56475 (Incorrect result of configure test for /dev/random…

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

libstdc++-v3/acinclude.m4

@@ -1739,7 +1739,12 @@ AC_DEFUN([GLIBCXX_CHECK_RANDOM_TR1], [
   AC_MSG_CHECKING([for "/dev/random" and "/dev/urandom" for TR1 random_device])
   AC_CACHE_VAL(glibcxx_cv_random_tr1, [
     if test -r /dev/random && test -r /dev/urandom; then
-      glibcxx_cv_random_tr1=yes;
+  ## For MSys environment the test above is detect as false-positive
+  ## on mingw-targets.  So disable it explicit for them.
+      case ${target_os} in
+	*mingw*) glibcxx_cv_random_tr1=no ;;
+	*) glibcxx_cv_random_tr1=yes ;;
+      esac
     else
       glibcxx_cv_random_tr1=no;
     fi

libstdc++-v3/configure

@@ -3530,11 +3530,11 @@ MAKEINFO=${MAKEINFO-"${am_missing_run}makeinfo"}
 
 # We need awk for the "check" target.  The system "awk" is bad on
 # some platforms.
-# Always define AMTAR for backward compatibility.
+# Always define AMTAR for backward compatibility.  Yes, it's still used
+# in the wild :-(  We should find a proper way to deprecate it ...
+AMTAR='$${TAR-tar}'
 
-AMTAR=${AMTAR-"${am_missing_run}tar"}
-
-am__tar='${AMTAR} chof - "$$tardir"'; am__untar='${AMTAR} xf -'
+am__tar='$${TAR-tar} chof - "$$tardir"' am__untar='$${TAR-tar} xf -'
 
 
 
@@ -26472,7 +26472,12 @@ $as_echo_n "checking for \"/dev/random\" and \"/dev/urandom\" for TR1 random_dev
 else
 
     if test -r /dev/random && test -r /dev/urandom; then
-      glibcxx_cv_random_tr1=yes;
+  ## For MSys environment the test above is detect as false-positive
+  ## on mingw-targets.  So disable it explicit for them.
+      case ${target_os} in
+	*mingw*) glibcxx_cv_random_tr1=no ;;
+	*) glibcxx_cv_random_tr1=yes ;;
+      esac
     else
       glibcxx_cv_random_tr1=no;
     fi