HLR_Tests.ttcn: suspend some compilation warnings

In the most use cases of f_SS_expect() we are not interested in
GSUP_PDU returned by this function. Calling it without storing
the returned value causes TTCN-3 compiler to complain:

  warning: The value returned by function
           `@HLR_Tests.f_SS_expect' is not used

Let's make use of previously unused variable 'res', and save
the returned GSUP_PDU to make the TTCN-3 compiler happy.

Change-Id: Ifda42aa18af8076013b436364513296b2b008731
1 file changed