Add fs->now to override time(0) in libext2fs

If fs->now is non-zero, use that as the time instead of the system
time when setting various filesystem fields (last modified time, last
write time, etc.)

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index 82cd9f1..5a0d100 100644
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -168,7 +168,7 @@
 	}
 
 	set_field(s_checkinterval, EXT2_DFL_CHECKINTERVAL);
-	super->s_mkfs_time = super->s_lastcheck = time(NULL);
+	super->s_mkfs_time = super->s_lastcheck = fs->now ? fs->now : time(NULL);
 
 	super->s_creator_os = CREATOR_OS;