Remove ENABLE_DRAFTS option

[stephanlachnit]

This option added ZMQ_BUILD_DRAFT_API to the compile definitions. However, this should be propagated by libzmq (see zeromq/libzmq#4323 and #477).

Closes #477.

[coveralls]

Pull Request Test Coverage Report for Build 6957349874

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.6%) to 86.354%

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Files with Coverage Reduction	New Missed Lines	%
zmq.hpp	6	82.88%

Totals
Change from base Build 6697216186:	-0.6%
Covered Lines:	848
Relevant Lines:	982

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💛 - Coveralls

[gummif]

This change will probably break something for someone using slightly older versions of libzmq.

[stephanlachnit]

This change will probably break something for someone using slightly older versions of libzmq.

Yes, I would recommend merging this change only after a new release of libzmq (the commit in question is not part of a release yet), since it is fairly reasonable to expect people not to take a new version of cppzmq and an old version libzmq.

[stephanlachnit]

@gummif since libzmq v4.3.5 has been released with zeromq/libzmq#4194 included, this can merged now

[stephanlachnit]

I also updated the CI to use 4.3.5. to actually use this change.

[gummif]

Sorry for the delay. I will see if I have time soon to do a review.

[stephanlachnit]

@gummif friendly ping to check this :) This is quite a small change