exconf.rb checks for libzmq.so installation

AUTHORS

@@ -18,6 +18,7 @@ Martin Hurton
 Martin Lucina
 Martin Sustrik
 Matus Hamorsky
+McClain Looney
 Pavel Gushcha
 Pavol Malosek
 Steven McCoy

bindings/ruby/extconf.rb

@@ -18,7 +18,11 @@
 
 require 'mkmf'
 dir_config('libzmq')
-have_library('libzmq')
-create_makefile("ruby")
+if have_library('libzmq', 'zmq_init')
+  puts "Cool, I found your zmq install..."
+  create_makefile("zmq")
+else
+  raise "Couldn't find zmq library. try setting --with-zmq-dir=<path> to tell me where it is."
+end