configure: Include AvailabilityMacros.h for osxvideo check

Otherwise MAC_OS_X_VERSION_MIN_REQUIRED might not be defined

diff --git a/configure.ac b/configure.ac
index bfccf6e..1bbdfa0 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -491,6 +491,7 @@ AG_GST_CHECK_FEATURE(OSX_VIDEO, [OSX video], osxvideosink, [
   dnl also require Snow Leopard or newer
 
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+        #include <AvailabilityMacros.h>
         #if MAC_OS_X_VERSION_MIN_REQUIRED < 1060
         #error Too old OSX version
         #endif