audit: Modify a set of system calls in audit class definitions

Each asm-generic/audit_xx.h defines a set of system calls for respective
audit permission class (read, write, change attribute or exec).
This patch changes two entries:

1) fchown in audit_change_attr.h
  Make fchown included by its own because in asm-generic/unistd.h, for example,
  fchown always exists while chown is optional. This change is necessary at
  least for arm64.

2) truncate64 in audit_write.h
  Add missing truncate64/ftruncate64 as well as truncate/ftruncate

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Eric Paris <eparis@redhat.com>