mke2fs,tune2fs: Enable huge_file, dir_nlink, and extra_isize features

Also change mke2fs.conf to enable huge_file,dir_nlink,extra_isize, and
uninit_bg by default for ext4 filesystems, and enable extra_isize in
the library as well.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 960f67b..7ee3dee 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -839,6 +839,9 @@
 		EXT4_FEATURE_INCOMPAT_FLEX_BG,
 	/* R/O compat */
 	EXT2_FEATURE_RO_COMPAT_LARGE_FILE|
+		EXT4_FEATURE_RO_COMPAT_HUGE_FILE|
+		EXT4_FEATURE_RO_COMPAT_DIR_NLINK|
+		EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE|
 		EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER|
 		EXT4_FEATURE_RO_COMPAT_GDT_CSUM
 };