Make KS_ZLIB flag public

[ithron]

When using the runtime with zlib support with cmake, the required KS_ZLIB flags is not propagated to the linking target.

[generalmimon]

@ithron Makes sense, thanks for the catch. Could you please fix the typo in the commit message? (It should be KS_ZLIB, not KS_ZLIP.)

I'm thinking how we can test this in CI - this is a very easy mistake to make, so we should have some sort of safety net to ensure it doesn't happen again.

If I understand correctly, the problem with -DKS_ZLIB having PRIVATE scope is that if you include kaitai/kaitaistream.h from an external project, then KS_ZLIB will not be defined and thus the process_zlib method will not exist?

kaitai_struct_cpp_stl_runtime/kaitai/kaitaistream.h

Lines 216 to 224 in 3350232

	#ifdef KS_ZLIB
	/**
	* Performs an unpacking ("inflation") of zlib-compressed data with usual zlib headers.
	* @param data data to unpack
	* @return unpacked data
	* @throws IOException
	*/
	static std::string process_zlib(std::string data);
	#endif

[ithron]

Fixed the typo.

Yes, that's exactly the issue.
I think the issue went unnoticed because the unit tests don't use the zlib function. Since the unit tests are linked against the runtime using cmake, they would not compile if one of the tests tried to access process_zlib().