add missing long_name for amv and dca encoder

Reviewed-by: Carl Eugen Hoyos
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dcaenc.c

@@ -583,4 +583,5 @@ AVCodec ff_dca_encoder = {
     .encode         = encode_frame,
     .capabilities   = CODEC_CAP_EXPERIMENTAL,
     .sample_fmts    = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
+    .long_name      = NULL_IF_CONFIG_SMALL("DCA (DTS Coherent Acoustics)"),
 };

libavcodec/mjpegenc.c

@@ -491,4 +491,5 @@ AVCodec ff_amv_encoder = {
     .encode         = amv_encode_picture,
     .close          = MPV_encode_end,
     .pix_fmts= (enum PixelFormat[]){PIX_FMT_YUVJ420P, PIX_FMT_YUVJ422P, -1},
+    .long_name      = NULL_IF_CONFIG_SMALL("AMV Video"),
 };