ProjectExplorer: use enum instead of QString for run mode

Change-Id: Ia906944a489b09afdea59f74afbf759b4caebe37
Reviewed-by: Aurindam Jana <aurindam.jana@nokia.com>
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/plugins/valgrind/callgrindtool.cpp

@@ -518,6 +518,11 @@ Core::Id CallgrindTool::id() const
     return "Callgrind";
 }
 
+ProjectExplorer::RunMode CallgrindTool::runMode() const
+{
+    return ProjectExplorer::CallgrindRunMode;
+}
+
 QString CallgrindTool::displayName() const
 {
     return tr("Valgrind Function Profiler");