Switch TypePointer::isunsigned from false to true, so CmpExp::toElem chooses the right operand for pointer comparisons. Fixes run/t/typeinfo_03_A,B,C,D.

module bug45;

void foo() {
    int bar;
    scope(exit) { bar++; }
    if (bar) return;
}

void main() {
    foo();
}