implement support for 3-digit MNC with leading zeros

Receive the mnc_3_digits flag from the PCU interface.

Bump the PCU interface to 9.
This is one part of the three identical pcuif_proto.h patches:
- I49cd762c3c9d7ee6a82451bdf3ffa2a060767947 (osmo-bts)
- I787fed84a7b613158a5618dd5cffafe4e4927234 (osmo-pcu)
- I78f30aef7aa224b2e9db54c3a844d8f520b3aee0 (osmo-bsc)

Add 3-digit flags and use the new RAI and LAI API from libosmocore throughout
the code base to be able to handle an MNC < 100 that has three digits (leading
zeros).

Depends: Id2240f7f518494c9df6c8bda52c0d5092f90f221 (libosmocore),
         Ib7176b1d65a03b76f41f94bc9d3293a8a07d24c6 (libosmocore)

Change-Id: I787fed84a7b613158a5618dd5cffafe4e4927234
diff --git a/tests/alloc/MslotTest.cpp b/tests/alloc/MslotTest.cpp
index 92f92fa..ebe04ca 100644
--- a/tests/alloc/MslotTest.cpp
+++ b/tests/alloc/MslotTest.cpp
@@ -37,6 +37,7 @@
 /* globals used by the code */
 void *tall_pcu_ctx;
 int16_t spoof_mnc = 0, spoof_mcc = 0;
+bool spoof_mnc_3_digits = false;
 
 static inline void test_all_classes(struct gprs_rlcmac_trx *trx, bool clear_masks)
 {