`".e".to_f` returns `NAN`

[dearblue]

% bin/mirb
mirb - Embeddable Interactive Ruby Shell

> ".e".to_f
 => NaN
> ".f".to_f
 => 0.0
> ".g".to_f
 => 0.0

CRuby 3.3 will all be converted to 0.0.

% irb33
irb(main):001> ".e".to_f
=> 0.0
irb(main):002> ".f".to_f
=> 0.0
irb(main):003> ".g".to_f
=> 0.0

Not sure if this is the cause, but passing ".e" to mrb_read_float() returns 0.1.

For reference, the original, https://github.com/mattn/strtod, returns 0.0.