Fix thinko that, with two map entries like shown below, in that order,

made autofs mix them up: the second one wasn't visible in ls(1) output,
and trying to access it would trigger mount for the first one.

foobar		host:/foobar
foo		host:/foo

MFC after:	3 days
Sponsored by:	The FreeBSD Foundation

sys/fs/autofs/autofs_vnops.c

@@ -544,6 +544,8 @@ autofs_node_find(struct autofs_node *parent, const char *name,
 
 	TAILQ_FOREACH(anp, &parent->an_children, an_next) {
 		if (namelen >= 0) {
+			if (strlen(anp->an_name) != namelen)
+				continue;
 			if (strncmp(anp->an_name, name, namelen) != 0)
 				continue;
 		} else {