*: optimize most of isXXXXX() macros

   text    data     bss     dec     hex filename
 824164     453    6812  831429   cafc5 busybox_old
 823730     453    6812  830995   cae13 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/loginutils/login.c b/loginutils/login.c
index ed2ab7f..70e8562 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -225,19 +225,22 @@
 	/* skip whitespace */
 	do {
 		c = getchar();
-		if (c == EOF) exit(EXIT_FAILURE);
+		if (c == EOF)
+			exit(EXIT_FAILURE);
 		if (c == '\n') {
-			if (!--cntdown) exit(EXIT_FAILURE);
+			if (!--cntdown)
+				exit(EXIT_FAILURE);
 			goto prompt;
 		}
-	} while (isspace(c));
+	} while (isspace(c)); /* maybe isblank? */
 
 	*buf++ = c;
 	if (!fgets(buf, size_buf-2, stdin))
 		exit(EXIT_FAILURE);
 	if (!strchr(buf, '\n'))
 		exit(EXIT_FAILURE);
-	while (isgraph(*buf)) buf++;
+	while ((unsigned char)*buf > ' ')
+		buf++;
 	*buf = '\0';
 }