Fix build warnings for gcc 6.3
Fix build warnings for gcc 6.3

Clean up some alias.

BUG=webm:1465

Change-Id: I99e186162db9f9e15375fef01564692434eda619

webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx