fix type switching over internal pointer union

Fixes #3947

tests/internal/test_union_switch.odin

@@ -0,0 +1,24 @@
+package test_internal
+
+import "core:log"
+import "core:testing"
+
+@(test)
+test_internal_pointer_union_switch :: proc(t: ^testing.T) {
+	foo: Maybe(^int)
+
+	switch _ in foo {
+	case ^int:
+		log.error("incorrect case")
+	case nil:
+	}
+
+	v := 1
+	foo = &v
+
+	switch _ in foo {
+	case ^int:
+	case nil:
+		log.error("incorrect case")
+	}
+}