string.c: Improve `fstring_hash` to reduce collisions

`rb_str_hash` doesn't include the encoding for ASCII only strings
because ASCII only strings are equal regardless of their encoding.

But in the case if the `fstring_table`, two identical ASCII strings
with different encodings aren't equal.

Given it's common to have both `:foo` (or `def foo`) and `"foo"`
in the same source code, this causes a lot of collisions in the
`fstring_table`.

0 files changed, 0 insertions, 0 deletions