reiserfs: Remove VLA from fs/reiserfs/reiserfs.h

Remove Variable Length Array from fs/reiserfs/reiserfs.h. EMPTY_DIR_SIZE
is used as an array size and as it is using strlen() it need not be
evaluated at compile time. Change it's definition to use sizeof() to
force evaluation of array length at compile time.
Signed-off-by: Kyle Spiers <kyle@spiers.me>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/reiserfs/reiserfs.h

@@ -1916,7 +1916,7 @@ struct reiserfs_de_head {
 
 /* empty directory contains two entries "." and ".." and their headers */
 #define EMPTY_DIR_SIZE \
-(DEH_SIZE * 2 + ROUND_UP (strlen (".")) + ROUND_UP (strlen ("..")))
+(DEH_SIZE * 2 + ROUND_UP (sizeof(".") - 1) + ROUND_UP (sizeof("..") - 1))
 
 /* old format directories have this size when empty */
 #define EMPTY_DIR_SIZE_V1 (DEH_SIZE * 2 + 3)