convert openbsc to use libosmocore-0.1.1 API

the 0.1.1 API is cleaned up and removes all exported global static
arrays (like rlm_cause_strs).  There are now proper accessor functions.
diff --git a/openbsc/configure.in b/openbsc/configure.in
index de0a9a9..27fb0ed 100644
--- a/openbsc/configure.in
+++ b/openbsc/configure.in
@@ -18,7 +18,7 @@
 AC_SEARCH_LIBS(crypt, crypt,
     [LIBCRYPT="-lcrypt"; AC_DEFINE([VTY_CRYPT_PW], [], [Use crypt functionality of vty.])])
 
-PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore = 0.1.0)
+PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 0.1.1)
 
 dnl checks for header files
 AC_HEADER_STDC