btrfs: make static code static & remove dead code

Big patch, but all it does is add statics to functions which
are in fact static, then remove the associated dead-code fallout.

removed functions:

btrfs_iref_to_path()
__btrfs_lookup_delayed_deletion_item()
__btrfs_search_delayed_insertion_item()
__btrfs_search_delayed_deletion_item()
find_eb_for_page()
btrfs_find_block_group()
range_straddles_pages()
extent_range_uptodate()
btrfs_file_extent_length()
btrfs_scrub_cancel_devid()
btrfs_start_transaction_lflush()

btrfs_print_tree() is left because it is used for debugging.
btrfs_start_transaction_lflush() and btrfs_reada_detach() are
left for symmetry.

ulist.c functions are left, another patch will take care of those.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index e95df43..01277b8 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -24,7 +24,7 @@
 #include "extent_io.h"
 #include "locking.h"
 
-void btrfs_assert_tree_read_locked(struct extent_buffer *eb);
+static void btrfs_assert_tree_read_locked(struct extent_buffer *eb);
 
 /*
  * if we currently have a spinning reader or writer lock
@@ -264,7 +264,7 @@
 	BUG_ON(!atomic_read(&eb->write_locks));
 }
 
-void btrfs_assert_tree_read_locked(struct extent_buffer *eb)
+static void btrfs_assert_tree_read_locked(struct extent_buffer *eb)
 {
 	BUG_ON(!atomic_read(&eb->read_locks));
 }