Output frames in first pass for VPX_DL_REALTIME.

Since combining VPX_DL_REALTIME with VPX_RC_FIRST_PASS is basically
nonsense, ignore the user's pass setting when this happens and
behave as if the requested encode is a single pass encode.

BUG=webm:1233

Change-Id: I5ee4c4e5838c4ca6d24988890aae490b10826db2
4 files changed