x86, setup: move isdigit.h to ctype.h, header files on top.

It is a subset of <ctype.h> functionality, so name it ctype.h. Also,
reorganize header files so #include statements are clustered near the
top as they should be.

Signed-off-by: H. Peter Anvin <[e-mail]>
LKML-Reference: <[e-mail]>

arch/x86/boot/boot.h

···
 #include "bitops.h"
 #include <asm/cpufeature.h>
 #include <asm/processor-flags.h>
+#include "ctype.h"
 
 /* Useful macros */
 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
···
 		     : "=qm" (diff), "+D" (s1), "+S" (s2), "+c" (len));
 	return diff;
 }
-
-#include "isdigit.h"
 
 /* Heap -- available for dynamic lists. */
 extern char _end[];

arch/x86/boot/compressed/misc.h

···
 #include <asm/bootparam.h>
 
 #define BOOT_BOOT_H
+#include "../ctype.h"
 
 /* misc.c */
 extern struct boot_params *real_mode;		/* Pointer to real-mode data */

arch/x86/boot/compressed/string.c

···
 #include "misc.h"
-
-#include "../isdigit.h"
 #include "../string.c"