malloc uintptr bytes, not ulong bytes.

Reference: /n/atom/patch/applied2013/fsmalnit
Date: Mon Jul 29 18:49:01 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/fs/pc/malloc.c	Mon Jul 29 18:48:39 2013
+++ /sys/src/fs/pc/malloc.c	Mon Jul 29 18:48:39 2013
@@ -25,7 +25,7 @@
  * end of the allocated memory.
  */
 void*
-ialloc(ulong n, int align)
+ialloc(uintptr n, int align)
 {
 	Mbank *b;
 	ulong p;