use a different build directory when building vendored Xcode projects
use a different build directory when building vendored Xcode projects

hboon/RubyMotion,hboon/RubyMotion,beni55/RubyMotion,hboon/RubyMotion,HipByte/RubyMotion,HipByte/RubyMotion,incbee/RubyMotion,jjaffeux/RubyMotion,jjaffeux/RubyMotion,HipByte/RubyMotion,incbee/RubyMotion,katsuyoshi/RubyMotion,katsuyoshi/RubyMotion,incbee/RubyMotion,jjaffeux/RubyMotion,jjaffeux/RubyMotion,incbee/RubyMotion,beni55/RubyMotion,beni55/RubyMotion,katsuyoshi/RubyMotion,katsuyoshi/RubyMotion,beni55/RubyMotion