Omit unneeded test in change_field()

* fields.c (change_field): Omit unnecessary test.

Signed-off-by: Paul Eggert <eggert@cs.ucla.edu>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com>

lib/fields.c

@@ -96,7 +96,7 @@ void change_field (char *buf, size_t maxsize, const char *prompt)
 		*cp = '\0';
 
 		cp = newf;
-		while (('\0' != *cp) && isspace (*cp)) {
+		while (isspace (*cp)) {
 			cp++;
 		}