add BSSLAP coding for Location Services

BSSLAP: there are APDUs transferred in BSSMAP-LE Connection Oriented
Information messages on Lb between BSC and SMLC.
Add BSSLAP coding for these APDU messages:
- TA Layer3
- TA Request
- TA Response, possibly containing Location Estimate coded in GAD
- Reject
- Reset (for intra-BSS handover during TA Request)
- Abort (for inter-BSS handover)

Add encoding and decoding tests.

Change-Id: I6409c4bcac402dc7626a3afce9081c59cd715fe8
diff --git a/include/Makefile.am b/include/Makefile.am
index fc1eec3..19d4043 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -92,6 +92,7 @@
                        osmocom/coding/gsm0503_interleaving.h \
                        osmocom/coding/gsm0503_coding.h \
                        osmocom/coding/gsm0503_amr_dtx.h \
+                       osmocom/gsm/bsslap.h \
                        osmocom/gsm/gad.h \
                        osmocom/gsm/gsm0808.h \
                        osmocom/gsm/gsm29205.h \
@@ -134,6 +135,8 @@
 		       osmocom/gsm/protocol/gsm_29_118.h \
                        osmocom/gsm/protocol/gsm_44_318.h \
                        osmocom/gsm/protocol/gsm_48_049.h \
+                       osmocom/gsm/protocol/gsm_48_071.h \
+                       osmocom/gsm/protocol/gsm_49_031.h \
                        osmocom/gsm/protocol/ipaccess.h \
                        osmocom/gsm/protocol/smpp34_osmocom.h \
                        osmocom/gsm/rsl.h \