xephyr: fix "set but not used warnings"

xephyr: fix "set but not used warnings"

ephyrvideo.c: In function 'ephyrPutVideo':
ephyrvideo.c:1009:42: warning: variable 'drw_h' set but not used
ephyrvideo.c:1009:31: warning: variable 'drw_w' set but not used
ephyrvideo.c:1009:20: warning: variable 'drw_y' set but not used
ephyrvideo.c:1009:9: warning: variable 'drw_x' set but not used
ephyrvideo.c: In function 'ephyrGetVideo':
ephyrvideo.c:1058:42: warning: variable 'drw_h' set but not used
ephyrvideo.c:1058:31: warning: variable 'drw_w' set but not used
ephyrvideo.c:1058:20: warning: variable 'drw_y' set but not used
ephyrvideo.c:1058:9: warning: variable 'drw_x' set but not used
ephyrvideo.c: In function 'ephyrPutStill':
ephyrvideo.c:1107:42: warning: variable 'drw_h' set but not used
ephyrvideo.c:1107:31: warning: variable 'drw_w' set but not used
ephyrvideo.c:1107:20: warning: variable 'drw_y' set but not used
ephyrvideo.c:1107:9: warning: variable 'drw_x' set but not used
ephyrvideo.c: In function 'ephyrGetStill':
ephyrvideo.c:1156:42: warning: variable 'drw_h' set but not used
ephyrvideo.c:1156:31: warning: variable 'drw_w' set but not used
ephyrvideo.c:1156:20: warning: variable 'drw_y' set but not used
ephyrvideo.c:1156:9: warning: variable 'drw_x' set but not used

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Robert Morell <rmorell@nvidia.com>