The PERFORMANCE_SCHEMA wrapper for mutex and rw-lock operations is
causing a lot of unlikely code to be inlined in each invocation.
The impact of this may have been emphasized in MariaDB 10.6, because
InnoDB now uses the common implementation of mutexes and condition
variables (MDEV-21452).

By default, we build with cmake -DPLUGIN_PERFSCHEMA enabled,
but at runtime no instrumentation will be enabled. Similar to
commit eba2d10a
we had better avoid inlining the rarely executed code in order to reduce
the code size and to improve the efficiency of the instruction cache.

This change was extensively tested by Axel Schwenke with and without
--enable-performance-schema (with no individual instruments enabled).
Removing the inline functions did not cause any performance regression
in either case. There seemed to be a tiny improvement, possibly due
to reduced code size and better instruction cache hit rate.