title: xamarin.forms project build error Output: max res 19, skipping values-v21 on Android project
body: <p>running the sample xamarin forms todo app and am getting this build error on Android.  Which frameworks/sdks do I need to install?</p>
  
  <p>I've installed Android SDK tools 24.0.2, platform tools 21 and build tools 21.1.2 - do I have to backwards match the build tool version with the target version I'm deploying to?  i.e. if I target kit kat do I have to use build tools version 19.1?</p>
  
  <p>here's the error</p>
  
  <pre><code>/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/Android/Xamarin.Android.Common.targets: Error: Tool exited with code: 1. Output: max res 19, skipping values-v21
  /Users/me/.local/share/Xamarin/Android.Support.v7.AppCompat/21.0.3/embedded/./res/drawable-xhdpi/abc_ab_share_pack_holo_dark.9.png: libpng warning: iCCP: Not recognizing known sRGB profile that has been edited
  </code></pre>