Build lib in a context of bigger project

[wsw2016]

If the cpp-client is integrated into a bigger project by
add_subdirectory(hazelcast-cpp-client)
the build fails as the compiler can not find *.h files.

Please replace CMAKE_SOURCE_DIR by PROJECT_SOURCE_DIR in lines 86 and 87 of the
hazelcast-cpp-client/CMakeLists.txt.

It solves the problem.

[ihsandemir]

Yes, that sounds good. Thanks for reporting.