1. use Regexp_processor_pcre::set_recursion_limit() to set the
recursion limit depending on the current available stack size
2. make pcre stack frame to be estimated no less than 500 bytes.
sometimes pcre estimates it too low, even though the manual
says 500+16 bytes (it was estimated only 188 for me, actual
frame size was 512).
3. do it for embedded too
Do not pass PCRE_UCP flag for binary data.
This makes bytes 0x80..FF not to belong to
generic character classes \d (digit) and \w (word character).
SELECT 0xFF RLIKE '\\w';
-> 0
Note, this change does not affect non-binary data,
which is still examined with the PCRE_UCP flag by default.
