import Oniguruma 5.9.5
Merge tag 'Oniguruma-5.9.5' into onig-5.9.x-mod

The original version of Oniguruma 5.9.5

Conflicts:
	regcomp.c
	st.h
remove unused variable

Do not use C99 style comment.
change the type of OnigCodePoint

There is no need of using 64-bit type for OnigCodePoint, 32-bit type is
enough.
[dist] update .editorconfig

Disable the trim_trailing_whitespace setting to reduce unnecessary
differences, because the original source codes of oniguruma contains
some trailing white spaces.