bgpd: Support matching on local preference in route-map

This patch adds support for matching on local preference in
BGP route-map.

Signed-off-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
diff --git a/doc/routemap.texi b/doc/routemap.texi
index 7938c96..b3ef7ca 100644
--- a/doc/routemap.texi
+++ b/doc/routemap.texi
@@ -151,6 +151,10 @@
 Matches the specified @var{metric}.
 @end deffn
 
+@deffn {Route-map Command} {match local-preference @var{metric}} {}
+Matches the specified @var{local-preference}.
+@end deffn
+
 @deffn {Route-map Command} {match community @var{community_list}} {}
 Matches the specified  @var{community_list}
 @end deffn