btrfs: rename struct-funcs.c to accessors.c

Rename struct-funcs.c to accessors.c so we can move the item accessors
out of ctree.h. accessors.c is a better description of the code that is
contained in these files.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/Makefile

@@ -24,7 +24,7 @@ obj-$(CONFIG_BTRFS_FS) := btrfs.o
 btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   file-item.o inode-item.o disk-io.o \
 	   transaction.o inode.o file.o tree-defrag.o \
-	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
+	   extent_map.o sysfs.o accessors.o xattr.o ordered-data.o \
 	   extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
 	   export.o tree-log.o free-space-cache.o zlib.o lzo.o zstd.o \
 	   compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \

fs/btrfs/accessors.c

@@ -4,7 +4,6 @@
  */
 
 #include <asm/unaligned.h>
-
 #include "messages.h"
 #include "ctree.h"