Summary: Reverting addition of posix-spawn for JRuby

The posix-spawn gem does work under JRuby (finally) but it's still
problematic at best. Its support for JRuby is mostly just for
conveinence (ex. tools like foreman) but it still uses a C-extension
under the hood.

While C-extensions work under JRuby, they're generally not
recommended unless you just don't have any other choice.

All that said, I'm actually reverting this primarily because Travis-CI
doesn't support C-extensions under JRuby and the builds won't pass with
this gem included.

CI for JRuby on our pull requests seems more important than the gains
we get from fork+exec, but hopefully can find a better solution to this
anyway.

Gemfile

@@ -18,8 +18,6 @@ group :development, :test do
   gem "ci_reporter"
   gem "ruby-prof" unless RUBY_PLATFORM =~ /java/
   gem "rake-compiler"
-  # posix-spawn: XCode 4.4 - brew install apple-gcc42 && export CC=/usr/local/bin/gcc-4.2 && bundle install
-  gem "posix-spawn" if RUBY_PLATFORM =~ /java/
 
   # Java
   platforms :jruby do

test/tools/mongo_config.rb

@@ -2,7 +2,6 @@
 require 'socket'
 require 'fileutils'
 require 'mongo'
-require 'posix/spawn' if RUBY_PLATFORM == 'java'
 
 $debug_level = 2
 STDOUT.sync = true
@@ -130,16 +129,11 @@ def initialize(cmd = nil)
       def start(verifies = 0)
         return @pid if running?
         begin
-          if RUBY_PLATFORM == 'java'
-            @pid = POSIX::Spawn::spawn(@cmd, [:in, :out, :err] => :close)
-          else
-            @pid = fork do
-              STDIN.reopen '/dev/null'
-              STDOUT.reopen '/dev/null', 'a'
-              STDERR.reopen STDOUT
-              exec cmd
-            end
-            #@pid = Process.spawn(@cmd, [:in, :out, :err] => :close)
+          @pid = fork do
+            STDIN.reopen '/dev/null'
+            STDOUT.reopen '/dev/null', 'a'
+            STDERR.reopen STDOUT
+            exec cmd
           end
           verify(verifies) if verifies > 0
           @pid