Upstream changes:
3.42 - 2018-04-21
* Include 'Changes' (this file) in the distribution.
3.41 - 2018-04-21
* Fix security problem: CWE-134: Use of Externally-Controlled Format String.
* Fix WIDEST_UTYPE.
* Add the following functions:
croak_sv, die_sv, mess_sv, warn_sv, mess, vmess, warn_nocontext,
croak_nocontext, croak_no_modify, croak_memory_wrap, croak_xs_usage.
* Delist functions listed as deprecated or unstable.
* (perl #132876) define API macros on if the NEED_ macro is defined.
* (perl #132876) only define croak_xs_usage()'s assert macro if cxu requested.
* (perl #132761) updates for older perls.
* Do not define PERL_MAGIC_qr more times.
* Do not mask Perl_warn_nocontext and Perl_croak_nocontext.
(Fixes compile errors on older threaded Perl versions.)
* Skip ASCII tests on non-ASCII platforms.
* Skip tests invalid on EBCDIC.
* Will now compile under C++11.
* Documentation improvements.