Fixes compatibility with C++11: (1 - 1) is no longer a NULL pointer constant.

src/gtest.cc

@@ -182,6 +182,10 @@ bool g_help_flag = false;
 
 }  // namespace internal
 
+static const char* GetDefaultFilter() {
+  return kUniversalFilter;
+}
+
 GTEST_DEFINE_bool_(
     also_run_disabled_tests,
     internal::BoolFromGTestEnv("also_run_disabled_tests", false),
@@ -208,7 +212,7 @@ GTEST_DEFINE_string_(
 
 GTEST_DEFINE_string_(
     filter,
-    internal::StringFromGTestEnv("filter", kUniversalFilter),
+    internal::StringFromGTestEnv("filter", GetDefaultFilter()),
     "A colon-separated list of glob (not regex) patterns "
     "for filtering the tests to run, optionally followed by a "
     "'-' and a : separated list of negative patterns (tests to "