Supress a warning mostly.

Reference: /n/patches.lsub.org/patch/trfsintptr
Date: Wed Apr 25 14:06:10 CES 2012
Signed-off-by: nemo@lsub.org

--- /sys/src/cmd/trfs.c	Thu Apr 12 12:26:02 2012
+++ /sys/src/cmd/trfs.c	Wed Apr 25 14:05:17 2012
@@ -41,7 +41,7 @@
 getaux(Fid* fp)
 {
 	assert(sizeof(ulong) <= sizeof(fp->aux));
-	return (ulong)fp->aux;
+	return (uintptr)fp->aux;
 }
 
 static void