This indicates integer counter mode being used and
helps disambiguate additional crypto suites in the future.
Renamed CALLS_SRTP_SUITE_AES_128_SHA1_80 → CALLS_SRTP_SUITE_AES_128_ICM_SHA1_80
and CALLS_SRTP_SUITE_AES_128_SHA1_32 → CALLS_SRTP_SUITE_AES_128_ICM_SHA1_32
gtk_test_init() ends up calling gtk_init() which tries opening
the default display. CI jobs sometimes seem to trip over this
even when run through xvfb-run. Therefore we use g_test_init()
instead.