Bundled zeromq and czmq have never used when ruby was built with --with-opt-dir configure option

[mrkn]

I use OS X El Capitan, homebrew, and rbenv.

I always build ruby with --with-opt-dir=$(brew --prefix) configure option.
Using this ruby, LIBPATH in Makefile generated by extconf.rb is:

LIBPATH =  -L. -L$(libdir) -L/opt/brew/lib -L/Users/mrkn/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/rbczmq-1.7.9/ext/rbczmq/dst/lib

As you can see -L/opt/brew/lib, that is -L$(brew --prefix), is specified before rbczmq/dst/lib directory. This means zeromq and czmq installed by homebrew are always used rather than bundled zeromq and czmq.