itch41: Add zlib support

This adds zlib support to tools/test-itch41.c. We can now directly
inspect data files provided on NASDAQ FTP without needing to uncompress
them first.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
FIX: Fix API return values for error handling

This makes the FIX API functions return zero on success and a negative
integer value on error. Also propagate error returned by
fix_session_send() to the callers where appropriate.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
FIX: Flip fix_session_admin return value

Make fix_session_admin() return type a 'bool' and flip the return value.
This avoids users confusing the return value to other API functions that
return zero on success and negative on error.

Reviewed-by: Marat Stanichenko <mstanichenko@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
FIX: Flip fix_session_keepalive return value

Same rationale as in commit 7de6c4d ("FIX: Flip fix_session_admin return
value") but for fix_session_keepalive().

Reviewed-by: Marat Stanichenko <mstanichenko@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>