Bug 414734, set up 2nd macosx buildslave for 1.8 staging, patch=armenzg, r=bhearsum

tools/buildbot-configs/automation/staging/master.cfg

@@ -222,7 +222,7 @@ c['builders'].append(
 c['builders'].append(
  { 
   'name': 'macosx_dep_build', 
-  'slavename': 'bm-xserve03',
+  'slavename': 'bm-xserve04',
   'builddir': 'macosx_dep_build', 
   'locks': [macosx_lock],
   'category': 'nightly',