Upgrade find librdkafka.cmake

[sknop]

Hi,

I had problems compiling your C++ wrapper because it could not find librdkafka. I found this new cmake extension that allowed me to find and compile the library: https://gist.github.com/matthew-d-jones/550ee6fa2f89610f88991513fa5d6cfc

(after adjusting the find:

-find_package(RdKafka REQUIRED ${FIND_PACKAGE_QUIET})
+find_package(LibRDKafka REQUIRED ${FIND_PACKAGE_QUIET})

)

Might be worth a look?

[accelerated]

The current FindRdKafka.cmake should work fine. It searches here to find all possible variations of the file such as librdkafka.so, librdkafka.a, rdkafka.a etc...
Note that your rdkafka library should be installed in the default place otherwise you should issue:
cmake -DRDKAFKA_ROOT_DIR=/some/other/dir ...