Increase the tolerance in wxStopWatch unit test.

Sleeping can take more time than expected when running on the build slaves,
probably because the machine is heavily loaded. Increase the tolerance to
prevent this from resulting in test failures.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70119 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/events/stopwatch.cpp

@@ -29,7 +29,7 @@
 namespace
 {
 
-const long tolerance = 10;  // in ms
+const long tolerance = 50;  // in ms
 const int sleepTime = 500;
 
 } // anonymous namespace