avcodec/avdct: add "xvid" alias AVOption and use FF_IDCT_XVID

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/avdct.c

@@ -59,7 +59,8 @@ static const AVOption avdct_options[] = {
 {"simplealpha", "experimental / for debugging", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_SIMPLEALPHA }, INT_MIN, INT_MAX, V|E|D, "idct"},
 #endif
 {"ipp", "experimental / for debugging", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_IPP }, INT_MIN, INT_MAX, V|E|D, "idct"},
-{"xvidmmx", "experimental / for debugging", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_XVIDMMX }, INT_MIN, INT_MAX, V|E|D, "idct"},
+{"xvid", "experimental / for debugging", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_XVID }, INT_MIN, INT_MAX, V|E|D, "idct"},
+{"xvidmmx", "experimental / for debugging", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_XVID }, INT_MIN, INT_MAX, V|E|D, "idct"},
 {"faani", "floating point AAN IDCT (experimental / for debugging)", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_FAAN }, INT_MIN, INT_MAX, V|D|E, "idct"},
 {"simpleauto", "experimental / for debugging", 0, AV_OPT_TYPE_CONST, {.i64 = FF_IDCT_SIMPLEAUTO }, INT_MIN, INT_MAX, V|E|D, "idct"},
 {NULL},