btrfs: add dependencies to fs.h and block-rsv.h

There's several structures that are embedded inside of fs_info.h, so if
we don't have all the proper includes when we include fs.h we'll get a
variety of compile errors.  I fixed this by adding a temporary c file
that just had #include "fs.h" and then added include files until the
compiler stopped complaining.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/block-rsv.h

@@ -4,6 +4,7 @@
 #define BTRFS_BLOCK_RSV_H
 
 struct btrfs_trans_handle;
+struct btrfs_root;
 enum btrfs_reserve_flush_enum;
 
 /*

fs/btrfs/fs.h

@@ -3,6 +3,14 @@
 #ifndef BTRFS_FS_H
 #define BTRFS_FS_H
 
+#include <linux/fs.h>
+#include <linux/btrfs_tree.h>
+#include <linux/sizes.h>
+#include "extent-io-tree.h"
+#include "extent_map.h"
+#include "async-thread.h"
+#include "block-rsv.h"
+
 #define BTRFS_MAX_EXTENT_SIZE SZ_128M
 
 #define BTRFS_OLDEST_GENERATION	0ULL