x86_64: include asm/bugs.h in bugs.c for check_bugs prototype

C files should include the header files that prototype their functions.

Eliminates a sparse warning:
warning: symbol 'check_bugs' was not declared. Should it be static?

Signed-off-by: Josh Triplett <josh@kernel.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86_64/kernel/bugs.c

@@ -8,6 +8,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <asm/alternative.h>
+#include <asm/bugs.h>
 #include <asm/processor.h>
 #include <asm/mtrr.h>