conditional flag evaluating to true when define doesn't exist

https://try.haxe.org/#43ddf946
I have a haxelib called 'db-core'

```hx
class Test {
static function main() {
#if "db-core" //same issue occurs with "db_core"
trace("db core is found");
#else
trace("db core not found");
#end
}
}
```

Outputs:
```
db core is found
```

Edit:
Actual solution is meant to be `#if db_core` but should the above still be evaluating to true?

Reproduce the behavior from the linked try.haxe.org example using the shown #if "db-core" and #if db_core forms. Trace how conditional-compilation expressions handle quoted, undefined names, then establish whether the observed result is intended and verify the chosen behavior with a regression test.

Written by the indexing model from the issue text.