btrfs: drop extern from function declarations

Extern for functions does not make any difference, there are only a few
so let's remove them before it's too late.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.h

@@ -83,8 +83,8 @@ static inline int le_test_bit(int nr, const u8 *addr)
 	return 1U & (addr[BIT_BYTE(nr)] >> (nr & (BITS_PER_BYTE-1)));
 }
 
-extern void le_bitmap_set(u8 *map, unsigned int start, int len);
-extern void le_bitmap_clear(u8 *map, unsigned int start, int len);
+void le_bitmap_set(u8 *map, unsigned int start, int len);
+void le_bitmap_clear(u8 *map, unsigned int start, int len);
 
 struct extent_state;
 struct btrfs_root;

fs/btrfs/xattr.h

@@ -23,13 +23,13 @@
 
 extern const struct xattr_handler *btrfs_xattr_handlers[];
 
-extern ssize_t btrfs_getxattr(struct inode *inode, const char *name,
+ssize_t btrfs_getxattr(struct inode *inode, const char *name,
 		void *buffer, size_t size);
-extern int btrfs_setxattr(struct btrfs_trans_handle *trans,
+int btrfs_setxattr(struct btrfs_trans_handle *trans,
 			    struct inode *inode, const char *name,
 			    const void *value, size_t size, int flags);
 
-extern int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
+int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
 				     struct inode *inode, struct inode *dir,
 				     const struct qstr *qstr);