CppTools: Ignore generated symbols in SearchSymbols

...e.g. qt_metacall() etc from the Q_OBJECT macro.

This affects the results of the cpp locator and find filters.

Change-Id: I2f9ff1210f3705baddadd486d700ee8be9a44a20
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>