Merge remote-tracking branch 'origin/5.12.1' into 5.12

Change-Id: I29bc61b996eac4cb7e0e3cddee2384b4e7fe4238

dist/changes-5.12.1

+Qt 5.12.1 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.12.0.
+
+For more details, refer to the online documentation included in this
+distribution. The documentation is also available online:
+
+http://doc.qt.io/qt-5/index.html
+
+The Qt version 5.12 series is binary compatible with the 5.11.x series.
+Applications compiled for 5.11 will continue to run with 5.12.
+
+Some of the changes listed in this file include issue tracking numbers
+corresponding to tasks in the Qt Bug Tracker:
+
+https://bugreports.qt.io/
+
+Each of these identifiers can be entered in the bug tracker to obtain more
+information about a particular change.
+
+****************************************************************************
+*                             Third-Party Code                             *
+****************************************************************************
+
+ - Update bundled libwebp to version 1.0.1
+ - Bundled libtiff was updated to version 4.0.10