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>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index faeaba8..3a6197a 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3055,7 +3055,7 @@
 	 * possible initialization would be here
 	 */
 
-	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
+	if (ext4_has_feature_extents(sb)) {
 #if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
 		printk(KERN_INFO "EXT4-fs: file extents enabled"
 #ifdef AGGRESSIVE_TEST
@@ -3082,7 +3082,7 @@
  */
 void ext4_ext_release(struct super_block *sb)
 {
-	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS))
+	if (!ext4_has_feature_extents(sb))
 		return;
 
 #ifdef EXTENTS_STATS