howto restrict Warnings to non-system files?

[Markus Werle]

Hi,

The very useful option -Weffc++ is of no use because of millions of
"errors" in gcc's own STL. For the normal user it would be nice to only
hear complains about her own code.

We all know that the STL sometimes needs to carefully violate
good C++ programming practice to achieve run-time efficiency.
(or can the STL be improved to quiet down gcc warnings? :-))

Markus