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/memchecktool.cpp

@@ -290,6 +290,11 @@ Core::Id MemcheckTool::id() const
     return "Memcheck";
 }
 
+ProjectExplorer::RunMode MemcheckTool::runMode() const
+{
+    return ProjectExplorer::MemcheckRunMode;
+}
+
 QString MemcheckTool::displayName() const
 {
     return tr("Valgrind Memory Analyzer");