Add changes file for 5.9.1

Change-Id: I45ca861c02b6d0016441dee3407995ba7ed1c182
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

dist/changes-5.9.1

+Qt 5.9.1 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.9.0.
+
+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 5.9 series is binary compatible with the 5.8.x series.
+Applications compiled for 5.8 will continue to run with 5.9.
+
+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.
+
+****************************************************************************
+*                          Library                                         *
+****************************************************************************
+
+QtBluetooth
+-----------
+
+ - Fixed several compiler warnings through the code base adopting new compilers
+   such as GCC 7.
+ - Added better documentation of GPL license usage via sdpscanner on BLueZ.
+   The GPL license usage is limited to separate process and does not taint
+   QtBluetooth users.
+ - Added limitation to do classic device discovery only inside
+   QBLuetoothServiceDiscoveryAgent. Prior to this change
+   QBLuetoothServiceDiscoveryAgent always performed a search for Low Energy
+   devices too. This is not necessary and reduces the time for SDP
+   discoveries.
+
+****************************************************************************
+*                      Platform Specific Changes                           *
+****************************************************************************
+
+Android
+-------
+
+ - [QTBUG-61392] Added workaround for swapped uuids obtained when doing SDP
+   discovery on Android 6.0.1 or later systems.
+ - Removed workaround for QBluetoothSocket that uses the private
+   BluetoothDevice.getServiceChannel() API from Android 6.0+ platforms.
+   The private API was removed in Android 6.0.
+ - [QTBUG-61321] Added code handler to catch BluetoothGatt.GATT_FAILURE.
+ - Fixed an issue where a QBLuetoothServiceDiscoveryAgent run would fail
+   to find any service because the last device for which the service discovery
+   was done failed.
+
+Linux/Bluez
+-----------
+
+ - [QTBUG-58941] Fixed failure to re-advertise peripheral after
+   QLowEnergyController disconnect and restart.
+ - [QTBUG-55150] Fixed handling of concurrent BTLE connections via QtBluetooth
+   and for example BlueZ tools like bluetoothctl. There can only be one connection
+   at a given time. Under the new behavior the current process closes every
+   BTLE connection not managed by itself.
+ - Fixed buffer overrun when handling GATT Blob read requests.
+ - [QTBUG-46776] Added code to detect whether a found Bluetooth address is random
+   or public. The standard BlueZ DBus interface does not expose this flag.
+   This requires CAP_NET_ADMIN permissions though.