Fix cd(), cdUp() QDir member functions docs regarding nonreadable dirs

The documentation implies that cd() and cdUp() functions return false if
the new directory is not readable, but that is not the case. It is an
obvious mistake in the documentation, because cd'ing into a nonreadable
directory is perfectly valid.

Provided also with a test to verify that cd() actually returns true with
nonreadable directories.

Change-Id: I4aa3e859b35c64266df510a203574e3701aea77c
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
clear OBJECTIVE_SOURCES as well

the newly added mac examples use it, so it needs to be grounded.

a more generic solution would be clearing out QMAKE_EXTRA_COMPILERS, but
many prf files will be loaded after us, possibly nullifying our effort.

Task-number: QTBUG-35680
Change-Id: I3aba7595898baac14bd41e9fae2ff24507187c6a
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Fix warning in QVariant test.

Values from different enums were compared.

Change-Id: I2faf73976e4b24abbdc915e8445256fe7a5be5bd
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Mac: Improve transformed QGraphicsProxyWidgets

Restore Mac code paths from Qt 4.

Task-number: QTBUG-29139
Change-Id: I2893ddf6015e2bda92d4a16980dbe2c9021eeef7
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Fix a possible crash in StyleSheetStyle

Task-number: QTBUG-35901
Change-Id: I72e82a166d30cf5e4dac2917c633c7cbd355c817
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>