10l: Don't spawn a subshell when disabling vdpau.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@20867 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -2483,8 +2483,8 @@ check_func XFixesGetCursorImage -lX11 -lXext -lXfixes
 
 check_cpp_condition \
     vdpau/vdpau.h "defined VDP_DECODER_PROFILE_MPEG4_PART2_ASP" ||
-    ( echolog "Please upgrade to libvdpau >= 0.2 if you would like vdpau support." &&
-      disable vdpau )
+    { echolog "Please upgrade to libvdpau >= 0.2 if you would like vdpau support." &&
+      disable vdpau; }
 
 enabled debug && add_cflags -g"$debuglevel" && add_asflags -g"$debuglevel"