Add now-required #include.

Fixes compiler warning induced by 808ea8f.

Author: tglsfdc

src/backend/commands/policy.c

@@ -29,6 +29,7 @@
 #include "nodes/makefuncs.h"
 #include "nodes/pg_list.h"
 #include "parser/parse_clause.h"
+#include "parser/parse_collate.h"
 #include "parser/parse_node.h"
 #include "parser/parse_relation.h"
 #include "rewrite/rewriteManip.h"