Added a stripModifiers() function to remove shared|const|immutable storage classes in D2 (should eventually be moved to a dhelpers file rather than llvm helpers). Replaced a few occurances of STCinvariant with STCimmutable.

module mini.norun_debug4;

void main()
{
    char c = 'c';
    wchar wc = 'w';
    dchar dc = 'd';

    int* fail = cast(int*) 1;
    *fail = 32;
}