kernel: use macros from compiler.h instead of __attribute__((...))

To increase compiler portability there is <linux/compiler.h> which
provides convenience macros for various gcc constructs.  Eg: __weak for
__attribute__((weak)).  I've replaced all instances of gcc attributes
with the right macro in the kernel subsystem.

Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/power/swap.c

@@ -101,7 +101,7 @@ struct swsusp_header {
 	unsigned int flags;	/* Flags to pass to the "boot" kernel */
 	char	orig_sig[10];
 	char	sig[10];
-} __attribute__((packed));
+} __packed;
 
 static struct swsusp_header *swsusp_header;