contrib: integrate RPM spec

Remove OpenSUSE bug report link, set version to @VERSION@, make it build
with CentOS 8 etc.

Disable lms, usrp1 for CentOS 8.

Related: OS#4550
Change-Id: Ie27fcc4f9033f0049507d9dcc295541ac0744c73
diff --git a/configure.ac b/configure.ac
index d0cfe44..07d4bf4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -336,4 +336,5 @@
 ])
 
 AC_OUTPUT(
-	doc/manuals/Makefile)
+	doc/manuals/Makefile
+	contrib/osmo-trx.spec)