qmake uses hardcoded path even when it doesn't have to

qmake shouldn't by default use the built-in Qt paths that are built in, it knows where it is (QCoreApplication::applicationFilePath) and where libs etc are relative to it (../lib, ../include). Only if the libraries are not found in those paths should the built-in paths be used.

The current mode makes it really hard to use a precompiled Qt that has been checked into a CVS across big teams.