range: Create range.c for code that should not be inline

range: Create range.c for code that should not be inline

g_list_insert_sorted_merged() is rather large to be an inline
function; move it to its own file.  range_merge() and
ranges_can_merge() can likewise move, as they are only used
internally.  Also, it becomes obvious that the condition within
range_merge() is already satisfied by its caller, and that the
return value is not used.

The diffstat is misleading, because of the copyright boilerplate.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1464712890-14262-2-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>