kcat built under Windows does not support the High-level KafkaConsumer mode

[drlsdee]

Steps to reproduce

1. Download the source code, latest release or even just pull from master
2. Do not touch, edit etc, just build with MS Visual Studio and MSBuild (successfully)
3. Try to subscribe to topics with High-level balanced KafkaConsumer
4. Enjoy=)

Cause

1. Various librdkafka version checks are performed in the kcat.h and kcat.c.
2. But it is the check of librdkafka version >= 0.9.0 to enable ENABLE_KAFKACONSUMER that is done in configure.self (lines 28..33).
3. Thus, at least when building with Visual Studio, the identifier ENABLE_KAFKACONSUMER remains unset.

Related problem

When building kcat on Windows with ENABLE_KAFKACONSUMER=1, error "E0020: identifier "LOG_DEBUG" is undefined" occurs.

Cause

1. The identifier LOG_DEBUG is defined in syslog.h.
2. When building under Windows, syslog.h is not included (see kcat.c, lines 29..38) because there is no version for Windows.

Possible solution

In win32_config.h (well, or somewhere else; it seems to me that since the problem occurs under Windows, it is best here)

1. define identifiers LOG_* as in syslog.h;
2. enable librdkafka version check >= 0.9.0 and definition of ENABLE_KAFKACONSUMER identifier