QWindowsVistaStyle: Fixed position of menu gutter when using a custom widget action.

The gutter position was hardcoded to 28 which fits when drawing
on the QMenu with a left margin of 3. It became offset when drawing
on a custom widget with no margin. Calculate position relative
to margin for left to right.

[ChangeLog][QtWidgets][QMenu][Windows] Fixed position of menu gutter when using a custom widget action.

Task-number: QTBUG-36218

Change-Id: Ibb34a9fba2bab7257482b80d2e51e76a9755345c
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Port Windows QPA plugin to new logger API.

Introduce logging categories and change most debug statements
to qCDebug().

Retrieve the filter rules from the environment variable
QT_QPA_VERBOSE (should be removed once the logging framework
offers a more convenient way of configuring).

Replace the old per-category variables controlling verboseness
of the output by a single variable which can be set on the command
line.

Change-Id: Iae55ecdb0e150efd165b7d3e90b371f72853f194
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Support negative layout spacings (do not assert)

This tests
* default spacing
* explicit positive spacing
* negative spacings

Negative spacings that causes the layout to shrink down to 0 or
a negative spacing are not supported.
(But make sure they don't crash the whole engine)

This is a partial cherry picked from
qtquickcontrols.git/bc973dcf2163b25f2db74d974b252384bbee8d80)

Only the Q_ASSERT had to be cherry-picked. This is because of that the
qgridlayoutengine* is moved to qtbase.
Therefore, any changes to qgridlayoutengine* won't be merged properly to
dev (they will be lost).

Task-number: QTBUG-35741
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>

Change-Id: I834f1efc11aca59a93c8d870f1a776f2f8810485
Reviewed-by: Caroline Chao <caroline.chao@digia.com>
iOS: Enable building of basic tests

Allows us to sanity check the iOS build in the CI.

Change-Id: I16f9bfafef3988dcab6efd3155503ca0d0b4d1d8
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Add freebsd-clang mkspec

clang is the default compiler on FreeBSD 10 (if not earlier).

Let's keep it unsupported for now. Can be promoted later.

Change-Id: I909953c986a3da09ce19d8f9f9ee2cc22c417abd
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Windows: Observe Qt::NoDropShadowWindowHint.

Task-number: QTBUG-36230

Change-Id: I8a9956c4b0ccd98b92f98107ea6dbbb08b296d09
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Add comment to moc output to simplify slots flags reading.

Change-Id: I5b8f63b6fa561c108abed4c2726b3aff99144fe2
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>