Use a single version number for program, library and SQL

Having the SQL on a different numbering scheme is useful to provide an ungrade
path. But pg_repack has no need of such a path as it can be uninstalled with
no problem, so we are not going to provide update script. Hence it's much
easier to have a single version number for everything.

lib/pg_repack.control.in

@@ -0,0 +1,5 @@
+# pg_repack extension
+comment = 'Reorganize tables in PostgreSQL databases with minimal locks'
+default_version = 'REPACK_VERSION'
+module_pathname = '$libdir/pg_repack'
+relocatable = false