It corresponds to TRANSSODIR, that contains `$(arch)`, so should
contain it as well.

Better fix for k-takata/Onigmo#107.

https://github.com/k-takata/Onigmo/commit/85393e4a63223b538529e7095255ce1153c09cff

* Multiplication result may overflow 'int' before it is converted to
  'OnigDistance'.
* Comparison is always true because code <= 122.
* This statement makes ExprStmt unreachable.
* Empty block without comment

https://github.com/k-takata/Onigmo/commit/387ad616c3cb9370f99d2b11198c2135fa07030f

... to conform to UTS 18 as mentioned in https://bugs.ruby-lang.org/issues/19417#note-3

https://unicode.org/reports/tr18/#word states word should match join_control chars.

It currently does not:

```ruby
[*0x0..0xD799, *0xE000..0x10FFFF].map { |n| n.chr 'utf-8' } => all_chars
all_chars.grep(/\p{join_control}/) => jc
jc.count # => 2
jc.grep(/\p{word}/).count # => 0
```