Move the huge page size defines into arch code

It's 2MB on x86-64 by default, and 4MB on x86.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/arch-x86_64.h b/arch-x86_64.h
index d53c9a2..4e0ad5f 100644
--- a/arch-x86_64.h
+++ b/arch-x86_64.h
@@ -25,6 +25,8 @@
 #define __NR_async_thread	283
 #endif
 
+#define	FIO_HUGE_PAGE		2097152
+
 #define FIO_HAVE_SYSLET
 
 #define nop	__asm__ __volatile__("rep;nop": : :"memory")