lavc/x264: Add compatibility values for coder options.

Fixes ticket #5142.

libavcodec/libx264.c

@@ -953,6 +953,8 @@ static const AVOption options[] = {
     { "default",          NULL, 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, VE, "coder" },
     { "cavlc",            NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 },  INT_MIN, INT_MAX, VE, "coder" },
     { "cabac",            NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 },  INT_MIN, INT_MAX, VE, "coder" },
+    { "vlc",              NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 },  INT_MIN, INT_MAX, VE, "coder" },
+    { "ac",               NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 },  INT_MIN, INT_MAX, VE, "coder" },
 
     { "x264-params",  "Override the x264 configuration using a :-separated list of key=value parameters", OFFSET(x264_params), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE },
     { NULL },