More Win64 test fixes

testsuite/tests/driver/all.T

@@ -295,7 +295,7 @@ test('2499', normal, compile_fail, [''])
 test('mode001', normal, run_command,
      ['$MAKE -s --no-print-directory mode001'])
 
-if config.platform == 'i386-unknown-mingw32':
+if config.os == 'mingw32':
      only_windows = normal
 else:
      only_windows = skip

testsuite/tests/lib/win32/all.T

 def win_only(opts):
-    if config.platform != "i386-unknown-mingw32" and \
-       config.platform != "i386-unknown-cygwin32":
-	opts.skip = 1
+    if config.os != "mingw32" and config.os != "cygwin32":
+        opts.skip = 1
 
 # This isn't a very good test to run automatically at the moment, since
 # it doesn't terminate