avcodec/openh264: return (DE|EN)CODER_NOT_FOUND if version check fails

A cosmetic change only, it basically just changes the user facing error message
to clients that interpret the errors to something that makes sense.

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavcodec/libopenh264dec.c

@@ -57,7 +57,7 @@ static av_cold int svc_decode_init(AVCodecContext *avctx)
     WelsTraceCallback callback_function;
 
     if ((err = ff_libopenh264_check_version(avctx)) < 0)
-        return err;
+        return AVERROR_DECODER_NOT_FOUND;
 
     if (WelsCreateDecoder(&s->decoder)) {
         av_log(avctx, AV_LOG_ERROR, "Unable to create decoder\n");

libavcodec/libopenh264enc.c

@@ -138,7 +138,7 @@ static av_cold int svc_encode_init(AVCodecContext *avctx)
     AVCPBProperties *props;
 
     if ((err = ff_libopenh264_check_version(avctx)) < 0)
-        return err;
+        return AVERROR_ENCODER_NOT_FOUND;
 
     if (WelsCreateSVCEncoder(&s->encoder)) {
         av_log(avctx, AV_LOG_ERROR, "Unable to create encoder\n");