Qbs: Enable exceptions where needed

Align with qmake project

Change-Id: Ic68619a0b5e3bf6052c8b52165337063a24e2b5d
Reviewed-by: Jake Petroules <jake.petroules@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>

src/plugins/valgrind/valgrind.qbs

@@ -13,6 +13,8 @@ QtcPlugin {
     Depends { name: "ProjectExplorer" }
     Depends { name: "TextEditor" }
 
+    cpp.enableExceptions: true
+
     Group {
         name: "General"
         files: [