* Set a null-ABI for toolchains where detection of ABI failed: This
  allows the user to select any tool chain.

* Warn if ABI detection fails by showing a message in the Qt version
  setup dialog

* Do not override the mkspec if the Qt version has a null ABI only:
  We (have to) trust the user to know what he is doing in that case.

* GCC: Add version information to GCC tool chain and use it to select
  the mkspec on Mac.

* GCC: Do not override mkspec if we do a cross-compile
  (and actually detect that).

* GCC: Leave out -32 or -64 from mkspec if the compiler binaries ABI
  matches the target ABI.

* Linux-generic is compatible with all other linuxes (both ways)
  The targets themselves do additional filtering and will remove
  anything that does not work for them anyway.

Task-number: QTCREATORBUG-5756
Task-number: QTCREATORBUG-5960
Change-Id: Ib3c0ac91f3aa8e2a823e3e9891a02bdccb97af14
Reviewed-on: http://codereview.qt-project.org/4281


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

Change-Id: Ie6275ebf6a49f0b1732cc146abeaa23c7b6eafd4
Reviewed-on: http://codereview.qt.nokia.com/1843


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

Also adjust qmldumptool to remove the dependency on qt4project/qmlproject, by
passing in the qtversion instead of figuring it out in qmldumptool.

Change-Id: Ie6ac582d36bfef290313c0716b33b62fcf42630c
Reviewed-on: http://codereview.qt.nokia.com/70


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

Actually pass on the base qt version value...
Also fix a small issue on the qt versions page that prevented the
invalid reason showing up for a nameless version

Task-Nr: QTCREATORBUG-4899

We can figure out now whether something was build with mingw or not.

Split up target specific code into subclasses. Also change
Qt4BuildConfiguration to allow a null qtversion.

Remove code that relied on always having a qt version.
Also make it possible to remove all qt versions.

Completly change the qt in path autodetection to be only
a fall back if no configuration was found.

Note: For now the old settings are not removed, as such 2.2 and master
can coexist.

Reviewed-By: hunger