Remove unused includes from test-fix-client.c

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Rename ITCH to NASDAQ ITCH

ITCH is a widely used name for market data protocols. Therefore, rename
ITCH to NASDAQ ITCH to avoid ambiguity.

Signed-off-by: Pekka Enberg <penberg@kernel.org>