[PATCH] Simplify STree_Find

Don't need to keep track of the parent node.

diff -urN a/common/shell.c head/common/shell.c
--- a/common/shell.c	2006-02-19 19:36:51.000000000 +1030
+++ head/common/shell.c	2006-02-21 17:50:57.000000000 +1030
@@ -21,6 +21,7 @@
  * This whole setup is butt-ugly. Proceed with caution.
  */
 
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -227,20 +228,18 @@
 struct stree_node *
 STree_Find(struct stree_root *root, const char *s)
 {
-    struct rb_node **p = &root->root.rb_node;
-    struct rb_node *parent = NULL;
+    struct rb_node *p = root->root.rb_node;
     struct stree_node *ret = NULL;
     struct stree_node *node;
     int cmp;
 
-    while (*p) {
-	parent = *p;
-	node = stree_entry(parent);
+    while (p) {
+	node = stree_entry(p);
 	cmp = strcasecmp(s, node->string);
 	if (cmp < 0)
-	    p = &(*p)->rb_left;
+	    p = p->rb_left;
 	else if (cmp > 0)
-	    p = &(*p)->rb_right;
+	    p = p->rb_right;
 	else {
 	    ret = node;
 	    break;