Checks whether replacement is a valid replacement string
(see Regex.replace), i.e. that all escape sequences in
it are valid.
If has_references is not NULL then replacement is checked
for pattern references. For instance, replacement text 'foo\n'
does not contain references and may be evaluated without information
about actual match, but '\0\1' (whole match followed by first
subpattern) requires valid glib.MatchInfo object.
Checks whether replacement is a valid replacement string (see Regex.replace), i.e. that all escape sequences in it are valid.
If has_references is not NULL then replacement is checked for pattern references. For instance, replacement text 'foo\n' does not contain references and may be evaluated without information about actual match, but '\0\1' (whole match followed by first subpattern) requires valid glib.MatchInfo object.