Allow to build samples via OpenCV binaries from distribution package
(find_package with OpenCV_DIR).

They're not listed in the documentation for the FindZLIB module,
so we shouldn't use them unless necessary.

exclude IlmImf/b44ExpLogTable.cpp from the build,

it's used originally to generate IlmImf/b44ExpLogTable.h, but not nessecary for the library.(probably only here for documentation

when included with static linking it introduces a problem with multiple definitions of main()