Update ustring data tables
normalization-data.lua is updated to Unicode 8.0.0 (libicu57).
charsets.lua is updated to match the character classes used by PCRE 8.35,
which seems to be Unicode 6.3.0.
upper.lua and lower.lua are still based on whatever ancient version of
Unicode is used by mb_strtoupper and mb_strtolower in HHVM 3.18.6.