libosmogsm: Introduce explicit list of exported symbols
There is now a "libosmogsm.map" file containing an explicit list of
to-be-exported symbols. This should prevent us from leaking non-static
symbols into the global namespace.
A similar scheme should be adopted by all other osmocom libraries
diff --git a/configure.ac b/configure.ac
index 0fea115..977eef9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,6 +14,7 @@
AC_PROG_INSTALL
LT_INIT
AC_PROG_LIBTOOL
+CHECK_GCC_FVISIBILITY
AC_CONFIG_MACRO_DIR([m4])