fix some assumptions that pointers can only be 32-bits. With this, we can

now compile:

static unsigned long X;
void test1() {
  X = 0;
}

into:

_test1:
        lis r2, ha16(_X)
        li r3, 0
        stw r3, lo16(_X)(r2)
        blr

Totally amazing :)

llvm-svn: 28839