MSVC: Fix the compilation of benchmark tests with strict string literals.

Introduced by 9f0e5d00ab51cc7c0dc87c8d72f48c4e6edaf120 .

Change-Id: I704501bd7e543d971f9b8c9e75746b5749126c5f
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@digia.com>

tests/benchmarks/gui/kernel/qapplication/main.cpp

@@ -60,7 +60,7 @@ void tst_qapplication::ctor()
 {
     // simulate reasonable argc, argv
     int argc = 1;
-    char *argv[] = { "tst_qapplication" };
+    char *argv[] = { const_cast<char*>("tst_qapplication") };
     QBENCHMARK {
         QApplication app(argc, argv);
     }