ext4: clean up feature test macros with predicate functions

ext4: clean up feature test macros with predicate functions

Create separate predicate functions to test/set/clear feature flags,
thereby replacing the wordy old macros.  Furthermore, clean out the
places where we open-coded feature tests.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
(cherry picked from commit e2b911c53584a92266943f3b7f2cdbc19c1a4e80)

Orabug: 25802481
CVE-2016-10208

Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>
 Conflicts:
	fs/ext4/namei.c
	fs/ext4/super.c