remove library version matching from qt.conf

remove library version matching from qt.conf

this feature was introduced in feb 2005 by Sam with this comment:
> I have implemented a versioning into the keys and do environment
> expansion there as well, these aren't immediately usefull but Marius
> and I agreed that distributors will probably want such features at
> times. The versioning fallbacks will be usefull to us over time no
> doubt.

imo the versioning is a contestant for the most useless feature ever:
- (linux) distributors couldn't care less - they simply configure qtcore
  correctly. additionally, the packaging policies state that no config
  files should live in the binary dir at all, so no qt.conf for them.
- ISVs don't care, because they ship their software with a particular qt
  version anyway.
- SDK distributors don't care, because it doesn't solve any real problem
  for them: a) they will isolate the (qmake) versions and b) a
  distinction based on version number (as opposed to build
  configuration) is utterly useless in the first place.

i left in the variable expansion, as it could at least theoretically be
useful for creating relocatable packages. debatable - the file it easy
enough to modify at installation time.

Change-Id: Ida8a50b16d55d8d8613d1a98a51df56753f6a6e3
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>