[hl] hl-check fails for switch statement with generic parameter

**Haxe Version:** 4.1.2
**HashLink Version:** 1.11.0, haxelib 0.1.0
```haxe
class SwitchTest
{
public static function main() { }

static function foo(bar:T)
{
// To reproduce the bug, there must be at least two non-default cases,
// and at least one of the case values must be negative.
switch (bar)
{
case -1: 0; // The expression doesn't matter.
case 1: 0;
default: 0;
}
}
}
```
Building this example with `haxe --hl test.hl -m SwitchTest -D hl-check` produces the following:
```
Error:
SwitchTest.hx:13: Check failure at fun@244 @1 - Register 2(f64) should be dyn and not f64
```
I originally discovered this bug when trying to build Flixel 4.8.0 for the HashLink target.