More H.264 (re #1390): added x264 in aconfigure

git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@3859 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/aconfigure.ac b/aconfigure.ac
index 3270863..2331545 100644
--- a/aconfigure.ac
+++ b/aconfigure.ac
@@ -828,6 +828,7 @@
 
 		dnl # libz, needed by newer ffmpeg
 		AC_CHECK_LIB(z, deflate)
+		AC_CHECK_LIB(x264, x264_free)
 
 		FFMPEG_PREFIX=""
     		if test "x$with_ffmpeg" != "xno" -a "x$with_ffmpeg" != "x"; then