Do not check_lib for -lva if vaapi is disabled, having -lva in extralibs

if vaapi is disabled is at best pointless.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@23417 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -2590,7 +2590,7 @@ for thread in $THREADS_LIST; do
 done
 
 check_lib math.h sin -lm
-check_lib va/va.h vaInitialize -lva
+disabled vaapi || check_lib va/va.h vaInitialize -lva
 
 check_mathfunc exp2
 check_mathfunc exp2f