Bug 520245: Avoid writing launch files with no changes

On shutdown of a debug session the launch files are written, often
(normally) with no changes. This commit prevents unneeded deltas
on the launch files and prevents a lot of the callbacks of launch
configurations changing. This also ameliorates the case in Bug 500988.

Change-Id: Iddbd9c5c5695dcd2d255cbc761a48316fa5acbb1
2 files changed