sndcp: Fixups for sndcp layer based on coverity-scan suggestions

- missing break in gprs_sndcp_pcomp.c, line 143
- string overflow in slhc_test.c, line 211
- sizeof mismatch in gprs_sndcp_xid.c, line 1369 and 1378
- mismatching signedness in gprs_sndcp_xid.c, line 1377
- needless < 0 comparison in gprs_sndcp_xid.c, line 477
- needless < 0 comparison in gprs_sndcp_xid.c, line 209
- missing returncode check in v42bis_test.c, line 320
- wrong pointer dereferentialization in gprs_sndcp_comp.c, line 73

Change-Id: I4f9adf251f5119e67ffe76baad6f1f996ac8dbad
diff --git a/openbsc/src/gprs/gprs_sndcp_pcomp.c b/openbsc/src/gprs/gprs_sndcp_pcomp.c
index 5f6fb2c..493b263 100644
--- a/openbsc/src/gprs/gprs_sndcp_pcomp.c
+++ b/openbsc/src/gprs/gprs_sndcp_pcomp.c
@@ -141,6 +141,7 @@
 	switch (pcomp_index) {
 	case 0:
 		type = SL_TYPE_IP;
+		break;
 	case 1:
 		type = SL_TYPE_UNCOMPRESSED_TCP;
 		break;