configure: Cygwin and MingW should try to use -Wdeclaration-after-statement.

configure.in

@@ -3174,6 +3174,7 @@ case "$host" in
                 ac_default_prefix=$BUILD_PREFIX
             fi
         fi
+        CheckDeclarationAfterStatement
         CheckDummyVideo
         CheckDiskAudio
         CheckDummyAudio