GSMTAP: Ad PTCCH as separate gsmtap category

This allows us to send GSMTAP for PTCCH only if requested by user/vty

Change-Id: Id720f4bebdce7f6152fbddddbe05036638c5866e
diff --git a/src/bts.h b/src/bts.h
index 66875f1..25193f9 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -51,6 +51,7 @@
 	PCU_GSMTAP_C_DL_CTRL		= 2,	/* downlink control blocks */
 	PCU_GSMTAP_C_DL_DATA_GPRS	= 3,	/* downlink GPRS data blocks */
 	PCU_GSMTAP_C_DL_DATA_EGPRS	= 4,	/* downlink EGPRS data blocks */
+	PCU_GSMTAP_C_DL_PTCCH		= 5,	/* downlink PTCCH blocks */
 
 	PCU_GSMTAP_C_UL_UNKNOWN		= 15,	/* unknown or undecodable uplink blocks */
 	PCU_GSMTAP_C_UL_DUMMY		= 16,	/* uplink dummy blocks */