Add standard include guard to asm-generic/signal and use compiler.h

Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

include/asm-generic/signal.h

+#ifndef __ASM_GENERIC_SIGNAL_H
+#define __ASM_GENERIC_SIGNAL_H
+
+#include <linux/compiler.h>
+
 #ifndef SIG_BLOCK
 #define SIG_BLOCK          0	/* for blocking signals */
 #endif
@@ -19,3 +24,5 @@ typedef __restorefn_t __user *__sigrestore_t;
 #define SIG_IGN	((__force __sighandler_t)1)	/* ignore signal */
 #define SIG_ERR	((__force __sighandler_t)-1)	/* error return from signal */
 #endif
+
+#endif /* __ASM_GENERIC_SIGNAL_H */