add spec.in file for RPM building

Change-Id: I7942b715a367f71b3fe74805f43dc45701983de8
diff --git a/configure.ac b/configure.ac
index e4d13c3..674dd1b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -109,4 +109,5 @@
         daemon/Makefile
 	doc/Makefile
 	doc/examples/Makefile
+	contrib/osmo-uecups.spec
         )