Log Message:
pcre2: update to 10.38

Version 10.38 01-October-2021
-----------------------------

As well as some bug fixes and tidies (as always, see ChangeLog for details),
the documentation is updated to list the new URLs, following the move of the
source repository to GitHub and the mailing list to Google Groups.

* The CMake build system can now build both static and shared libraries in one
go.

* Following Perl's lead, \K is now locked out in lookaround assertions by
default, but an option is provided to re-enable the previous behaviour.