MDEV-22203: WSREP_ON is unnecessarily expensive to evaluate

This is a backport of the applicable part of
commit 93475aff8de80a0ef53cbee924bcb70de6e86f2c and
commit 2c39f69d34e64a5cf94720e82e78c0ee91bd4649
from 10.4.

Before 10.4 and Galera 4, WSREP_ON is a macro that points to
a global Boolean variable, so it is not that expensive to
evaluate, but we will add an unlikely() hint around it.

WSREP_ON_NEW: Remove. This macro was introduced in
commit c863159c320008676aff978a7cdde5732678f975
when reverting WSREP_ON to its previous definition.

We replace some use of WSREP_ON with WSREP(thd), like it was done
in 93475aff8de80a0ef53cbee924bcb70de6e86f2c. Note: the macro
WSREP() in 10.1 is equivalent to WSREP_NNULL() in 10.4.

Item_func_rand::seed_random(): Avoid invoking current_thd
when WSREP is not enabled.

0 files changed, 0 insertions, 0 deletions