[PowerPC][AIX][NFC] Add zero-sized by val params to cc test.

The zero sized structs force creation of a stack object of size 1, align
8 in the locals area, but otherwise have no effect on the calling convention
code. i.e. They consume no registers or stack space in the paramater save area.

The 32-bit codegen has 8 bytes of padding to fit the new stack object so
stack size stays the same. 64-bit codegen has no padding in the stack
frames allocated so 8 bytes is added, and becuase of 16-byte aligned
stack, the stack size increases from 112 bytes to 128.