lang/pypy: update to 5.4.1

ChangeLog:

• Update list of contributors in documentation and LICENSE file, this was unfortunately left out of 5.4.0.
• Allow tests run with -A to find libm.so even if it is a script not a dynamically loadable file
• Bump sys.setrecursionlimit() when translating PyPy, for translating with CPython
• Tweak a float comparison with 0 in backendopt.inline to avoid rounding errors
• Fix for an issue for translating the sandbox
• Fix for and issue where unicode.decode('utf8', 'custom_replace') messed up the last byte of a unicode string sometimes
• Update built-in cffi to version 1.8.1
• Explicitly detect that we found as-yet-unsupported OpenSSL 1.1, and crash translation with a message asking for help porting it
• Fix a regression where a PyBytesObject was forced (converted to a RPython object) when not required, reported as issue #2395