Work around compiler errors on newer versions of gcc

[nickmarden]

Fixes #85

Unfortunately the "fix" mentioned in the #85 thread:

CFLAGS=-Wno-error=format-overflow gem install zookeeper --version 1.4.11

did not fix the issue for me in the context of bundle install, because this had the effect of setting that value of CFLAGS for all native extensions in my bundle install, not just zookeeper. This in turn broke some of my other bundle installs.

Futhermore, bundle config build.zookeeper --with-cflags=... does not fix the issue because those bundle CFLAG settings are passed only to the zookeeper gem itself, which (because of the way ext/extconf.rb is written) does not pass the provided cflags into the zkc-3.4.5 build where the problem is really occurring.

So at the end of the day, the right solution seemed to be to patch the offending code, which leads to this one-liner PR.

[nickmarden]

The observed CI failure (https://travis-ci.org/github/zk-ruby/zookeeper/builds/718060713?utm_source=github_status&utm_medium=notification) seems to be unrelated to this PR but instead caused by unavailable binary builds of Ruby 1.8.7:

https://travis-ci.org/github/zk-ruby/zookeeper/jobs/718060715
https://travis-ci.org/github/zk-ruby/zookeeper/jobs/718060716

[miry]

The same patch tested in https://github.com/NixOS/nixpkgs/pull/68642/files

[nickmarden]

@slyphon @eric @berlincount Thanks for your awesome package, we use it a lot at Avvo!

I'm not sure how to proceed now that this PR is passing CI. I think it's pretty safe but of course the maintainers may feel otherwise. Any guidance?

[nickmarden]

@slyphon @eric @berlincount I'm unclear on how to proceed here. Could I please have guidance?

[berlincount]

I'm not really involved, so I can't comment - and shall unsubscribe from this issue :)

[malmckay]

@nickmarden Thanks for the fix! We've switched to building with GitHub Actions, so I've merged this in #97 to handle that change.