simplify checks for I_CLEAR/I_FREEING

add I_CLEAR instead of replacing I_FREEING with it.  I_CLEAR is
equivalent to I_FREEING for almost all code looking at either;
it's there to keep track of having called clear_inode() exactly
once per inode lifetime, at some point after having set I_FREEING.
I_CLEAR and I_FREEING never get set at the same time with the
current code, so we can switch to setting i_flags to I_FREEING | I_CLEAR
instead of I_CLEAR without loss of information.  As the result of
such change, checks become simpler and the amount of code that needs
to know about I_CLEAR shrinks a lot.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 6c023a3..08140f1 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -84,7 +84,7 @@
 	struct gfs2_skip_data *data = opaque;
 
 	if (ip->i_no_addr == data->no_addr) {
-		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)){
+		if (inode->i_state & (I_FREEING|I_WILL_FREE)){
 			data->skipped = 1;
 			return 0;
 		}