[PyQt] Support for relocated Qt installations.

[Giulio Eulisse]

> The build system on my project is similar in that I can build stuff in one place and install it wherever
> I want. Relocating Qt caused me no end of headaches. All of the documented or suggested solutions
> never seemed to work quite right.

I feel your pain... ;) 


> I "solved" this problem by using the qpatch program, included with qt-creator.

Given that qtcreator is not part of our distribution, that would be not so straight forward for us, but thanks anyways for your suggestion. I'll keep this in mind, in case we encounter problems with the current solution (we have not so far). 

BTW, does that work even in the case the relocated path is longer than the original one?

Ciao,
Giulio