gtk2/libmozgtk.so is not stripped

In projects/firefox/build we use this loop to strip and generate debuginfo for the firefox *.so files we include in the bundle:

for LIB in Browser/*.so Browser/firefox.real Browser/plugin-container Browser/updater

I think we should add gtk2/*.so to this loop.

In the same place we also remove the RUNPATH in case selfrando is used.