Import git-version-gen and update AC_INIT()

In AC_INIT(), it still stated openbts.  Let's clean this up and use
the same method of version generation that we use in all other osmocom
projects, too.

Change-Id: Ie7ae0585955aebdc3950b1dd8bff0d1fff3be212
diff --git a/configure.ac b/configure.ac
index 43b5403..6e59fa2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,7 +18,9 @@
 dnl along with this program.  If not, see <http://www.gnu.org/licenses/>.
 dnl
 
-AC_INIT(openbts,P2.8TRUNK)
+AC_INIT([osmo-trx],
+	m4_esyscmd([./git-version-gen .tarball-veresion]),
+	[openbsc@lists.osmocom.org])
 AC_PREREQ(2.57)
 AC_CONFIG_SRCDIR([Transceiver52M/Makefile.am])
 AC_CONFIG_AUX_DIR([.])