SNDCP: add V.42bis data compression functionality

 - Add compression control for V.42bis Add code to handle compression
   (gprs_sndcp_dcomp.c/h)
 - Add Adjustments in SNDCP
 - Add VTY commands

Change-Id: I6d36cbdf2f5c5f83ca9ba57c70452f02b8582e7e
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 3970ba6..d228b39 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -72,6 +72,7 @@
 	gprs_sgsn.c \
 	gprs_sndcp.c \
 	gprs_sndcp_comp.c \
+	gprs_sndcp_dcomp.c \
 	gprs_sndcp_pcomp.c \
 	gprs_sndcp_vty.c \
 	gprs_sndcp_xid.c \