Fix wxCALL_FOR_EACH() to work with more than 2 arguments with MSVC.

Due to a bug in MSVC handling of __VA_ARGS__ (see
https://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement)
wxCALL_FOR_EACH() didn't work correctly as long as more than two arguments
were used with it.

Work around the bug by protecting __VA_ARGS__ from being incorrectly passed as
a single token to the macro being called on every step: this was already done
for wxCALL_FOR_EACH itself with wxCALL_FOR_EACH_, but we need to do it for all
the helper macros too.

Also add a test checking that this does, actually, work.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77689 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/misc/misctests.cpp

@@ -35,11 +35,15 @@ public:
 private:
     CPPUNIT_TEST_SUITE( MiscTestCase );
         CPPUNIT_TEST( Assert );
+#ifdef HAVE_VARIADIC_MACROS
+        CPPUNIT_TEST( CallForEach );
+#endif // HAVE_VARIADIC_MACROS
         CPPUNIT_TEST( Delete );
         CPPUNIT_TEST( StaticCast );
     CPPUNIT_TEST_SUITE_END();
 
     void Assert();
+    void CallForEach();
     void Delete();
     void StaticCast();
 
@@ -75,6 +79,20 @@ void MiscTestCase::Assert()
     wxSetAssertHandler(oldHandler);
 }
 
+#ifdef HAVE_VARIADIC_MACROS
+void MiscTestCase::CallForEach()
+{
+    #define MY_MACRO(pos, str) s += str;
+
+    wxString s;
+    wxCALL_FOR_EACH(MY_MACRO, "foo", "bar", "baz");
+
+    CPPUNIT_ASSERT_EQUAL( "foobarbaz", s );
+
+    #undef MY_MACRO
+}
+#endif // HAVE_VARIADIC_MACROS
+
 void MiscTestCase::Delete()
 {
     // Allocate some arbitrary memory to get a valid pointer: