[dist] regenerate autotools files

Regenerate autotools files using the following command:
$ autoreconf -vfi
Fix a renumbering bug in condition regexp with a named capture.

Submitted by Ippei Obayashi in https://bugs.ruby-lang.org/issues/8583.
Merge pull request #20 from knu/fix_cond+named

Fix a renumbering bug in condition regexp with a named capture.
remove trailing white space
ignore oniguruma.pc
update documents and version number (5.13.5)

* Update the version number to 5.13.5.
* Update LTVERSION to 5:0:5.
Merge tag 'Onigmo-5.13.5' into tmp/ruby-2.0.x

Onigmo 5.13.5