Move sha2.h to platform code

FreeBSD has its own sha routines that the port uses.

Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #9530

include/os/linux/zfs/sys/Makefile.am

@@ -1,5 +1,6 @@
 KERNEL_H = \
 	$(top_srcdir)/include/os/linux/zfs/sys/policy.h \
+	$(top_srcdir)/include/os/linux/zfs/sys/sha2.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/trace_acl.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/trace_arc.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/trace_common.h \

include/os/linux/zfs/sys/sha2.h

@@ -27,11 +27,7 @@
 #ifndef _SYS_SHA2_H
 #define	_SYS_SHA2_H
 
-#ifdef  _KERNEL
 #include <sys/types.h>		/* for uint_* */
-#else
-#include <stdint.h>
-#endif
 
 #ifdef	__cplusplus
 extern "C" {

include/sys/Makefile.am

@@ -60,7 +60,6 @@ COMMON_H = \
 	$(top_srcdir)/include/sys/rrwlock.h \
 	$(top_srcdir)/include/sys/sa.h \
 	$(top_srcdir)/include/sys/sa_impl.h \
-	$(top_srcdir)/include/sys/sha2.h \
 	$(top_srcdir)/include/sys/skein.h \
 	$(top_srcdir)/include/sys/spa_boot.h \
 	$(top_srcdir)/include/sys/spa_checkpoint.h \