cvtpcre now correctly handles \= data modifiers
cvtpcre now correctly handles \= data modifiers

\= splits data and modifiers in the pcre2 test driver.  cvtpcre was not
handling this correctly.  Now:

- \= is no longer turned into '='
- \= splits the data from the modifiers.
- if any unsupported modifiers are present, cvtpcre skips the match

- no modifiers are currently supported

katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm