Fix shader-interpreter non-IEEE outputs (#459)

* Re-enable non-IEEE shader test

* Fix shader-interpreter RCP/RSQ output

Handle the `-0.0` special-case

* Fix shader-interpreter MIN/MAX output

Takes advantage of min/max's properties regarding non-finites to return
NaN depending on its input position:
```
max(NaN, 2.f) -> NaN
max(2.f, NaN) -> 2
min(NaN, 2.f) -> NaN
min(2.f, NaN) -> 2
```

* Fix shader-interpreter FLR indexing bug

`3 - 1` should be `3 - i`

tests/shader.cpp

@@ -113,7 +113,7 @@ SHADER_TEST_CASE("RCP", "[shader][vertex]") {
 		{nihstro::OpCode::Id::END},
 	});
 
-	// REQUIRE(shader->RunScalar({-0.0f}) == INFINITY); // Violates IEEE
+	REQUIRE(shader->runScalar({-0.0f}) == INFINITY);
 	REQUIRE(shader->runScalar({0.0f}) == INFINITY);
 	REQUIRE(shader->runScalar({INFINITY}) == 0.0f);
 	REQUIRE(std::isnan(shader->runScalar({NAN})));