MINOR: pattern: make the pattern matching function return a pointer to the matched element

This feature will be used by the CLI to look up keys.
diff --git a/src/acl.c b/src/acl.c
index ef6b4a3..b033f2a 100644
--- a/src/acl.c
+++ b/src/acl.c
@@ -977,7 +977,7 @@
 					continue;
 				}
 
-				acl_res |= pat2acl(pattern_exec_match(&expr->pat, &smp, NULL));
+				acl_res |= pat2acl(pattern_exec_match(&expr->pat, &smp, NULL, NULL, NULL));
 				/*
 				 * OK now acl_res holds the result of this expression
 				 * as one of ACL_TEST_FAIL, ACL_TEST_MISS or ACL_TEST_PASS.