Initialize LLVM target and asmprinter for the native and extra targets. Uses some CMake hackery to get the native LLVM target name, since it only provides a conveniance function for initializing the native target and not the native asmprinter.

interface I {}
class A : I {}
class B : A {}

void main () {
    A a = new A;
    I i = a;

    assert(!cast(B)a);
    assert(!cast(B)i);
}