contrib: integrate RPM spec

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

Related: OS#4550
Change-Id: Ib2da03980d99f12ab36ca5d5fdde92ddbefb040b
diff --git a/.gitignore b/.gitignore
index e2546a0..a1cec37 100644
--- a/.gitignore
+++ b/.gitignore
@@ -49,3 +49,5 @@
 debian/.debhelper
 debian/debhelper*
 debian/files
+
+contrib/osmo-remsim.spec