Log Message:
oniguruma: updated to 6.9.4

Release 6.9.4
(Almost same as Release Candidate 3)
NEW API: RegSet (set of regexes)
Fixed CVE-2019-19012
Fixed CVE-2019-19203 (Does not affect UTF-8, UTF-16 and UTF-32 encodings)
Fixed CVE-2019-19204 (Affects only PosixBasic, Emacs and Grep syntaxes)
Fixed CVE-2019-19246
Fixed some problems (found by libFuzzer test)