library/GSUP_Types: add dest name to some messages

Prepare for upcoming D-GSM test, that lets OsmoHLR act as proxy. It
forwards the messages based on the destination name, so the testsuite
must set it correctly.

Related: OS#4380
Change-Id: I7623b7a7c7a18ba18a38d0834979d18ab0fbb961
1 file changed