avoid cast on l-value

svn: r2278

src/mzscheme/gc2/fnls.c

@@ -30,6 +30,7 @@ static int num_fnls;
 
 #define Tree Fnl
 #define Splay_Item(t) ((unsigned long)t->p)
+#define Set_Splay_Item(t, v) (t)->p = (void *)v
 #include "../sgc/splay.c"
 
 void GC_set_finalizer(void *p, int tagged, int level, void (*f)(void *p, void *data), 

src/mzscheme/sgc/splay.c

@@ -49,6 +49,7 @@ struct tree_node {
     void *data;
 };
 # define Splay_Item(t) t->item
+# define Set_Splay_Item(t, v) t->item = v
 #endif
 
 static Tree * splay (unsigned long i, Tree * t) {
@@ -98,7 +99,7 @@ static Tree * splay (unsigned long i, Tree * t) {
 static Tree * splay_insert(unsigned long i, Tree * new, Tree * t) {
 /* Insert i into the tree t, unless it's already there.    */
 /* Return a pointer to the resulting tree.                 */
-    Splay_Item(new) = i;
+    Set_Splay_Item(new, i);
     if (t == NULL) {
 	new->left = new->right = NULL;
 	return new;