lib: memscan() fixlet

Generic version doesn't trucate second argument to char.

Older brother memchr() does as do s390, sparc and i386 assembly versions.

Fortunately, no code passes c >= 256.

Link: https://lkml.kernel.org/r/YLv4cCf0t5UPdyK+@localhost.localdomain
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/string.c

@@ -977,7 +977,7 @@ void *memscan(void *addr, int c, size_t size)
 	unsigned char *p = addr;
 
 	while (size) {
-		if (*p == c)
+		if (*p == (unsigned char)c)
 			return (void *)p;
 		p++;
 		size--;