Fix a latent bug in the asm code. I think that technically, using "*m0" instead of "*0" allows LLVM to pick between using the same memory as output 0 and using a new memory location. (So far I haven't been able to construct a testcase that actually breaks because of this, though)

module union4;

union U {
    struct { float x,y,z; }
    float[3] xyz;
}

void main() {
    const float[3] a = [1f,2,3];
    U u = U(1,2,3);
    assert(u.xyz == a);
    assert(u.x == 1);
    assert(u.y == 2);
    assert(u.z == 3);
}