tests/rlcmac: fix malformed MS RA capability in testRAcap()

Long story short: as it turns out the test vector '12a5146200'O
has been generated by TITAN, and it's malformed. The length
indicator it contains must be at least 29 bits, not 21. This
field is calculated by TITAN automatically, so I guess there
is a bug somewhere in its RAW encoder implementation.

It's funny that Wireshark decodes the old malformed vector without
any problems if it's encapsulated into the BSSGP DL-UNITDATA. The
reason for that is because BSSGP dissector does not actually use
the CSN.1 codec and relies on its own hand-written parser [1],
which does not respect the length constraints.

Furthermore, table 10.5.146/3GPP TS 24.008, describing the format
of MS Radio Access Capability IE, has the following comment:

  < Multislot capability struct > ::=
    { 0 | 1 < HSCSD multislot class : bit (5) > }
    ...
  -- error: struct too short, assume features do not exist

so ideally our CSN.1 decoder should be more tolerant to the old
malformed vector, but unfortunately error handling is not implemented.

[1] See de_gmm_ms_radio_acc_cap() in epan/dissectors/packet-gsm_a_gm.c.

Change-Id: I5f810397b8d09c18e069168023429f6a4d899c86
diff --git a/tests/rlcmac/RLCMACTest.ok b/tests/rlcmac/RLCMACTest.ok
index 2d27ca4..96c1bfb 100644
--- a/tests/rlcmac/RLCMACTest.ok
+++ b/tests/rlcmac/RLCMACTest.ok
@@ -124,4 +124,7 @@
 vector1 == vector2 : TRUE
 *** testCsnLeftAlignedVarBmpBounds ***
 *** testRAcap ***
-decode_gsm_ra_cap fails? yes
+GPRS multislot class = 3
+EGPRS multislot class = 0
+Test decoding of a malformed vector (short length indicator)
+decode_gsm_ra_cap() returns -5