Amend commit b853b4fd88b441f36eeb7eabdce79918ef10538a
that was reverted in commit 29150e23912ef6e1fe386f53b778c9a5551c4790.
recv_parse_log_recs(): Do check for corrupted redo log or file
system before checking for len==0, but only read *ptr if
it is not past the end of the buffer (end_ptr).
recv_parse_log_rec(): Report incorrect redo log type
in a consistent way with recv_parse_or_apply_log_rec_body().
This is a follow-up to commit f30c5af42e4e72a3a0d8d5fb7b9fc884a249f292.
The Pool poisoning that was introduced in MDEV-15030 introduced
race conditions in AddressSanitizer builds, because concurrent
poisoning and unpoisoning were not prevented by any synchronization
primitive.
Pool::get(): Protect the unpoisoning by m_lock_strategy.
Pool::mem_free(): Protect the poisoning by m_lock_strategy.
Pool::putl(): Renamed from put(), because now the caller is
responsible for invoking m_lock_strategy.