patch-libavcodec-detection

--- configure.ac~	2012-07-15 22:27:11.195257379 +0100
+++ configure.ac	2012-07-15 22:24:34.308268675 +0100
@@ -276,7 +276,7 @@
 AC_CHECK_LIB(avutil,av_malloc,,AC_MSG_WARN(libavutil.a may be required for MPEG streaming))
 # Don't bother to warn about this one
 AC_CHECK_LIB(avcore,av_image_copy,,)
-AC_CHECK_LIB(avcodec,avcodec_init,,AC_MSG_WARN(libavcodec.a is required for MPEG streaming))
+AC_CHECK_LIB(avcodec,avcodec_open,,AC_MSG_WARN(libavcodec.a is required for MPEG streaming))
 AC_CHECK_LIB(avformat,av_new_stream,,AC_MSG_WARN(libavformat.a is required for MPEG streaming))
 AC_CHECK_LIB(avdevice,avdevice_register_all,,AC_MSG_WARN(libavdevice.a may be required for MPEG streaming))
 AC_CHECK_LIB(swscale,sws_scale,,,-lswscale)