go/types, types2: type inference fails when passing the same generic function twice

```Go
package p

func f(func(int), func(string)) {}

func g[P any](P) {}

func _() {
	f(g, g)
}
```
produces
```
x.go:8:7: type func[P any](P) of g does not match func(string)
```

Analysis (by @findleyr): we need to rename `g`'s type parameters to avoid conflicts.