Add changes file for 5.8.0

Change-Id: I6468b30b6dca4276298e452811ac141677bd6120
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

dist/changes-5.8.0

+Qt 5.8 introduces many new features and improvements as well as bugfixes
+over the 5.7.x series. 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 5.8 series is binary compatible with the 5.7.x series.
+Applications compiled for 5.7 will continue to run with 5.8.
+
+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.
+
+androiddeployqt
+---------------
+
+ - [QTBUG-54147] Fixed problem with ANDROID_DEPLOYMENT_DEPENDENCIES where
+   last entry in directory would be skipped.
+
+lupdate
+-------
+
+ - [QTBUG-34092] Fixed parsing of #includes without a space before the
+   file name
+ - [QTBUG-53206] Added qrc resource file support
+
+linguist
+--------
+
+ - [QTBUG-35144] Translation validation now recognizes the %Ln marker
+ - [QTBUG-52020] Fixed widget alignment in length variants view
+ - [QTBUG-56374] Fixed descriptions of file formats not being translated
+
+macdeployqt
+-----------
+
+ - Added option '-libpath' to search libraries in a custom path.