[PyQt] Smaller PyQt Modules

[Phil Thompson]

Tonight's SIP and PyQt snapshots will support the building of PyQt with the
redefine-protected-as-public hack. It is enabled by default for Linux and
MacOS/X. If other platforms use a C++ ABI that allows this then let me know
and I'll enable it for those by default as well.

As a result QtGui.so is 28% smaller on my development system - I was
surprised it made so much difference.

Phil