BUG/MEDIUM: regex: initialize the match array earlier during boot

BUG/MEDIUM: regex: initialize the match array earlier during boot

As reported by @zhanhb in github issue #3410, since 3.3 with commit
fda6dc959 ("MINOR: regex: use a thread-local match pointer for pcre2"),
the local_pcre2_match array is initialized too late for use by Lua. If
a lua-load makes use of regex, it may segfault (actually using PCRE2
is fine but PCRE2_JIT will crash):

Let's change the init sequence so that the first thread's context is
initialized early at boot and other threads are initialized when they
are created. For lua-load-per-thread, all extra threads will run on
the first thread's temporary storage during init but that's not a
problem since the sole purpose is to avoid concurrent accesses.

Thanks to @zhanbb for the detailed report and quick tests. This needs
to be backported to 3.3.