This patch adds support of b8g8r8x8 pixel format for SDL2.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-id: 20160517072848.4540.34695.stgit@PASHA-ISP
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>