winex11: Fix ctrl-<symbol> to generate codes below 0x20 where necessary.

[Huw Davies]

On 28 May 2015, at 12:04, Marvin wrote:
> === wvistau64 (32 bit input) ===
> input.c:731: Test failed:  0 (a4/0): 10 from 01 -> 00 unexpected
> input.c:731: Test failed:  0 (a4/0): 11 from 01 -> 00 unexpected
> input.c:731: Test failed:  0 (a4/0): a0 from 01 -> 00 unexpected
> input.c:731: Test failed:  0 (a4/0): a2 from 01 -> 00 unexpected

These are unrelated to my tests.

Huw.