Use C++11 unconditionally for qbs build of auto tests

... and valgrind fake tool.

Change-Id: I36d4e696ab0f37067eca639cb79613879d0fc990
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>

src/tools/valgrindfake/valgrindfake.qbs

@@ -5,6 +5,7 @@ CppApplication {
     consoleApplication: true
     destinationDirectory: project.ide_bin_path
     Depends { name: "Qt"; submodules: ["network", "xml"]; }
+    cpp.cxxLanguageVersion: "c++11"
     files: [
         "main.cpp",
         "outputgenerator.h", "outputgenerator.cpp"

tests/auto/extensionsystem/plugin.qbs

@@ -15,5 +15,6 @@ DynamicLibrary {
         project.buildDirectory + "/" + project.libDirName + "/qtcreator",
         project.buildDirectory + "/" + project.libDirName + "/qtcreator/plugins"
     ].concat(additionalRPaths)
+    cpp.cxxLanguageVersion: "c++11"
     property pathList additionalRPaths: []
 }