duplicate less work while handling -qconfig

Change-Id: I8ba6b866f98c9fe7609af71c168023097e32828c
Reviewed-by: Tasuku Suzuki <stasuku@gmail.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
turn makeabs into a proper cleanPath()

normalize away all ".." and ".".
fewer surprises that way.

Change-Id: Iaa56c634aed5c8351966eaea7a73b85cb8235ead
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
bring the windows configure -qconfig handling in line with the unix one

on the way, this significantly simplifies the code.

Change-Id: I24f0a517e62cc4b913ffef5cab096e721653c013
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Don't use NO_DEFAULT_PATH on mac when finding GL headers and libraries.

The paths may be relative to a sysroot or osx SDK. The existing logic
assumed that we always get fully resolved absolute paths from qmake.
However, qmake populates and uses the -isysroot option separately.

Task-number: QTBUG-32308

Change-Id: Ia23600cdc047d0844bfec32dd4feae3a2b5c95c0
Reviewed-by: James Turner <james.turner@kdab.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>