clang15 finally errors on old prototype definations.

Its also a lot fussier about variables that aren't used
as is the case a number of time with loop counters that
aren't examined.

RocksDB was complaining that its get_range function was
declared without the array length in ha_rocksdb.h. While
a constant is used rather than trying to import the
Rdb_key_def::INDEX_NUMBER_SIZE header (was causing a lot of
errors on the defination of other orders). If the constant
does change can be assured that the same compile warnings will
tell us of the error.

The ha_rocksdb::index_read_map_impl DBUG_EXECUTE_IF was similar
to the existing endless functions used in replication tests.
Its rather moot point as the rocksdb.force_shutdown test that
uses myrocks_busy_loop_on_row_read is currently disabled.