remove sample utf-8 code that's not part of the standard library

src/multibyte/decode.c

@@ -1,47 +0,0 @@
-/* 
- * This code was written by Rich Felker in 2010; no copyright is claimed.
- * This code is in the public domain. Attribution is appreciated but
- * unnecessary.
- */
-
-#include <stdlib.h>
-#include <inttypes.h>
-#include <wchar.h>
-#include <errno.h>
-
-#include "internal.h"
-
-/* Decodes UTF-8 byte-by-byte. The c argument must be initialized to 0
- * to begin decoding; when finished it will contain the Unicode scalar
- * value decoded. Return value is 1 if finished, 0 if in-progress, and
- * -1 if an invalid sequence was encountered. After an invalid sequence,
- * the state (in c) automatically resets to 0 if a continuation byte was
- * expected to facilitate a calling idiom of immediately retrying a
- * failed decode call after processing the invalid sequence. If the
- * second try fails, the byte is invalid as a starter as well.
- *
- * A trivial usage idiom is:
- *       while (src<end && (n=decode(dst, *src))>=0) 1[dst+=n]=0, src++;
- */
-
-int decode(unsigned *c, unsigned b)
-{
-	if (!*c) {
-		if (b < 0x80) {
-			*c = b;
-			return 1;
-		} else if (b-SA >= SB-SA) {
-			*c = FAILSTATE;
-			return -1;
-		}
-		*c = bittab[b-SA];
-		return 0;
-	}
-
-	if (OOB(*c,b)) {
-		*c = 0;
-		return -1;
-	}
-	*c = *c<<6 | b-0x80;
-	return !(*c&(1U<<31));
-}