Debugger: Use gdb's tooltip expression fixup for CDB and editor.

Factor out to watchutils.

Change-Id: I8cf316be819d765dcea964ac6405bfa9b075de59
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/debuggerplugin.cpp

@@ -1140,6 +1140,7 @@ public slots:
             int line, column;
             exp = cppExpressionAt(textEditor, tc.position(), &line, &column);
         }
+        exp = fixCppExpression(exp);
         if (exp.isEmpty())
             return;
         currentEngine()->watchHandler()->watchExpression(exp);