debian/changelog: document changes to debian/rules

debian/changelog

@@ -38,6 +38,10 @@ mumble (1.3.0~git20190114.9fcc588+dfsg-1) UNRELEASED; urgency=medium
     - Remove 48-systemd-workaround.diff (incorporated upstream)
     - Remove 50-zeroc-ice-lib-move.diff (similar fix incorporated upstream)
     - Remove 54-fix-boost-ftbfs.diff (incorporated upstream)
+  * debian/rules:
+    - Enable QT_SELECT=qt5 to force use of Qt5's qmake rather than Qt4's
+    - Switch qmake-qt4 to qmake in override_dh_auto_configure section
+    - Add CONFIG*=dpkg-buildflags in override_dh_auto_configure section
   * debian/upstream:
     - Remove signing-key.asc due to having to repack upstream tarball
       which will cause the PGP signature check to fail