[Development] buildsystem branches (about to be) integrated

[Oswald Buddenhagen]

moin,

the buildsystem branch of qtbase is currently being integrated. this is
~120 commits worth of qmake & project file fixes and cleanups. there are
some changes to how modularization (in particular configure tests) is
handled, and cross-building should be supported without hacks finally.

the immediate impact:
- lots of build scripts which employ various hacks will instantly
  break. don't panic and (mostly) just delete some code from them.
  use
      configure -xplatform <spec> -sysroot <root>
      make
  as you would intuitively expect. don't play tricks with funny qmake
  and make invocations.
- the other modules will spit out lots of warnings now.
  *DON'T* do anything about them for now. i have patches prepared for
  all modules already. i will explicitly add the module owners to the
  reviews. *don't* stage anything yourself.
  once my patches are through, there will be still some warnings left.
  you'll be invited to fix them at this point.
- some build configurations will work even worse than before until
  everything is integrated. the only variants which are expected to be
  safe are developer builds without -prefix and module-by-module builds
  with -prefix.

catch me on IRC if something breaks for you and no obvious solution
seems to help. but remember that not every breakage is due to this
branch being integrated. ;)