Work around an LLVM bug by not referring to globals from metadata. This was only used for consistency checking anyway. For the LLVM bug, see http://llvm.org/PR4180 / http://llvm.org/PR4046

struct Vertex {
    uint[1] c;
}

void main() {
    uint[1] c = 0xffffffff;

    auto v = Vertex(c);

    assert(v.c[0] == 0xffffffff);  // fails in LDC
}