Warn if version is greater than 2.x.x

[Simon Strandgaard]

I just installed the latest stable: Stable release 3.2 (release candidate 2)

(I did not realize it was a release candidate until much later).

With zeromq 3.2.1 I was unable to run a gem install zmq. I got this message

PROMPT> gem install zmq
Fetching: zmq-2.1.4.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing zmq:
    ERROR: Failed to build gem native extension.

        /Users/neoneye/.rvm/rubies/ruby-1.9.3-p286/bin/ruby extconf.rb
checking for zmq.h... yes
checking for zmq_init() in -lzmq... yes
Cool, I found your zmq install...
creating Makefile

make
compiling rbzmq.c
rbzmq.c:968:7: error: use of undeclared identifier 'ZMQ_RECOVERY_IVL_MSEC'
        case ZMQ_RECOVERY_IVL_MSEC:
             ^
rbzmq.c:990:10: error: use of undeclared identifier 'ZMQ_HWM'
    case ZMQ_HWM:
         ^
rbzmq.c:991:10: error: use of undeclared identifier 'ZMQ_SWAP'
    case ZMQ_SWAP:
         ^
rbzmq.c:995:10: error: use of undeclared identifier 'ZMQ_MCAST_LOOP'
    case ZMQ_MCAST_LOOP:
         ^
rbzmq.c:1292:10: error: use of undeclared identifier 'ZMQ_HWM'
    case ZMQ_HWM:
         ^
rbzmq.c:1293:10: error: use of undeclared identifier 'ZMQ_SWAP'
    case ZMQ_SWAP:
         ^
rbzmq.c:1297:10: error: use of undeclared identifier 'ZMQ_MCAST_LOOP'
    case ZMQ_MCAST_LOOP:
         ^

With zeromq 2.2.0 I had no problems running gem install zmq.

[Brian Buchanan]

Superseded by #25