It is one of these changes that should have never worked but did
for a long time. Only recently a corrupted GTP message was seen.
The code in ccd2312d10 tried to
solve the right problem but was deeply flawed.
* Make the code operate on the copied message and not the original
one that is deleted by the underlaying layers on return
* Add an out variable to determine if the msgb should be deleted
and assume that by default it will be deleted.
Change-Id: I564526e7cde2b8a2f0ce900492cd38fc23c176a7
725f3f1de0