Crash with structures containing generic pointers

The following code:
```cpp
typedef struct { float *data; } Data;

kernel void k(global float *data_out_raw) {
Data d {data_out_raw};
}
```
When compiled with `-cl-std=CLC++ -inline-entry-points` results in
```
Assertion failed: (castIsValid(op, S, Ty) && "Invalid cast!"), function Create, file Instructions.cpp, line 3682.
```