tools/nolibc: string: Remove the `_nolibc_memcpy_down()` function

This nolibc internal function is not used. Delete it. It was probably
supposed to handle memmove(), but today the memmove() has its own
implementation.
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

tools/include/nolibc/string.h

@@ -39,16 +39,6 @@ void *_nolibc_memcpy_up(void *dst, const void *src, size_t len)
 	return dst;
 }
 
-static __attribute__((unused))
-void *_nolibc_memcpy_down(void *dst, const void *src, size_t len)
-{
-	while (len) {
-		len--;
-		((char *)dst)[len] = ((const char *)src)[len];
-	}
-	return dst;
-}
-
 #ifndef NOLIBC_ARCH_HAS_MEMMOVE
 /* might be ignored by the compiler without -ffreestanding, then found as
  * missing.