Bug 1003711 - [RTSP] Build Darwin Streaming Server on B2G emulator

Change-Id: Iab903f897fe514c2cec1d9b9eab79fb52617d3b8
Merge pull request #200 from ethantseng/bug-1003711-fix

Bug 1003711 - Part 1: Add darwinstreamingserver to b2g-manifest. r=vicamo