tccgen: 32bits: fix PTR +/- long long

Previously in order to perform a ll+ll operation tcc
was trying to 'lexpand' PTR in gen_opl which did
not work well.  The case:


    int printf(const char *, ...);
    char t[] = "012345678";

    int main(void)
    {
        char *data = t;
        unsigned long long r = 4;
        unsigned a = 5;
        unsigned long long b = 12;

        *(unsigned*)(data + r) += a - b;

        printf("data %s\n", data);
        return 0;
    }

tests/tests2/87_ptr_longlong_arith32.expect

@@ -0,0 +1 @@
+data = "0123-5678"