Convert macros to static inline functions (block.h)
Remove BlockIdIsValid(), which wasn't used and is unnecessary.
Remove BlockIdCopy(), which wasn't used and can be done by struct
assignment.
(BlockIdEquals() also isn't used, but seems reasonable to keep
around.)
Reviewed-by: Amul Sul <sulamul@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/
5b558da8-99fb-0a99-83dd-
f72f05388517%40enterprisedb.com