Add changes file for Qt 5.12.4

Change-Id: Icb632a9e34f7c507153291322edc6f5c008b7b21
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
 

dist/changes-5.12.4

+Qt 5.12.4 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.12.0 through 5.12.3.
+
+For more details, refer to the online documentation included in this
+distribution. The documentation is also available online:
+
+https://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.
+
+****************************************************************************
+*                              Qt 5.12.3 Changes                           *
+****************************************************************************
+
+QtBluetooth
+-----------
+
+ - Fixed a memory leak in QBluetoothServiceDiscoveryAgent on Android.
+
+ - [QTBUG-75035] Improved likelihood of
+   QBluetoothSocket::connectToService(QBluetoothServiceInfo,..) succeeding when
+   QBluetoothServiceInfo::socketProtocol() returns a non-RFCOMM type. Since Android
+   does not support anything but RFCOMM it always assumes RFCOMM.
+
+ - Fixed reading of descriptor values on WinRT.
+
+ - [QTBUG-75043] Fixed behavior when a peripheral changes its service list at runtime
+
+ - [QTBUG-75278] Fixed socket leak when running QLowEnergyController Peripheral mode
+   on Linux.