MINOR: pattern: find element in a reference

This function can be used to look for an entry in either an ACL or a
MAP.
diff --git a/include/proto/pattern.h b/include/proto/pattern.h
index fdf9598..e6ceba8 100644
--- a/include/proto/pattern.h
+++ b/include/proto/pattern.h
@@ -181,6 +181,7 @@
 struct pat_ref *pat_ref_lookupid(int unique_id);
 struct pat_ref *pat_ref_new(const char *reference, const char *display, unsigned int flags);
 struct pat_ref *pat_ref_newid(int unique_id, const char *display, unsigned int flags);
+struct pat_ref_elt *pat_ref_find_elt(struct pat_ref *ref, const char *key);
 int pat_ref_append(struct pat_ref *ref, char *pattern, char *sample, int line);
 int pat_ref_add(struct pat_ref *ref, const char *pattern, const char *sample, char **err);
 int pat_ref_set(struct pat_ref *ref, const char *pattern, const char *sample, char **err);
diff --git a/src/pattern.c b/src/pattern.c
index 3238fbb..16aa09f 100644
--- a/src/pattern.c
+++ b/src/pattern.c
@@ -1408,6 +1408,23 @@
 	return 1;
 }
 
+/*
+ * find and return an element <elt> matching <key> in a reference <ref>
+ * return NULL if not found
+ */
+struct pat_ref_elt *pat_ref_find_elt(struct pat_ref *ref, const char *key)
+{
+	struct pat_ref_elt *elt;
+
+	list_for_each_entry(elt, &ref->head, list) {
+		if (strcmp(key, elt->pattern) == 0)
+			return elt;
+	}
+
+	return NULL;
+}
+
+
   /* This function modify the sample of the first pattern that match the <key>. */
 static inline int pat_ref_set_elt(struct pat_ref *ref, struct pat_ref_elt *elt,
                                   const char *value, char **err)