postscript: update for 32-bit Rune

http://codereview.appspot.com/117062

src/cmd/postscript/common/rune.h

@@ -4,16 +4,4 @@
  *
  */
 
-#define RUNELIB		1
-
-#ifdef RUNELIB
-typedef unsigned short	Rune;
-
-enum
-{
-	UTFmax		= 3,		/* maximum bytes per rune */
-	Runesync	= 0x80,		/* cannot represent part of a utf sequence (<) */
-	Runeself	= 0x80,		/* rune and utf sequences are the same (<) */
-	Runeerror	= 0xFFFD		/* decoding error in utf */
-};
-#endif
+#include <utf.h>