Only check for libossaudio if compiling wineoss.drv and the headers
are recent enough. Also only wineoss.drv needs to be linked with
libossaudio so put the link options in OSS4_LIBS.
Signed-off-by: Francois Gouget <fgouget@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>