Now it takes two arguments: A regexp and a string to match against.
_parse_varvals itself was split in three: _preprocess_varvals,
_parse_varvals, and _process_val.
This also modifies the three places that call _parse_varvals; For
two, no real changes were needed, but parse_mysqld() required a fix
to deal with the two final lines of mysqld --help --verbose:
To see what values a running MySQL server is using, type
'mysqladmin variables' instead of 'mysqld --verbose --help'.