avdevice/decklink_dec: fix leaks on error

In case of errors in this function, the allocated context
was not properly freed in several cases.

Signed-off-by: Marton Balint <cus@passwd.hu>
(cherry picked from commit 8e76c993013d6dd9382774d1716d8fe2421c42bd)

libavdevice/decklink_dec.cpp

@@ -1114,7 +1114,8 @@ av_cold int ff_decklink_read_header(AVFormatContext *avctx)
             break;
         default:
             av_log(avctx, AV_LOG_ERROR, "Value of channels option must be one of 2, 8 or 16\n");
-            return AVERROR(EINVAL);
+            ret = AVERROR(EINVAL);
+            goto error;
     }
 
     /* Check audio bit depth option for valid values: 16 or 32 */
@@ -1124,18 +1125,20 @@ av_cold int ff_decklink_read_header(AVFormatContext *avctx)
             break;
         default:
             av_log(avctx, AV_LOG_ERROR, "Value for audio bit depth option must be either 16 or 32\n");
-            return AVERROR(EINVAL);
+            ret = AVERROR(EINVAL);
+            goto error;
     }
 
     /* List available devices. */
     if (ctx->list_devices) {
         ff_decklink_list_devices_legacy(avctx, 1, 0);
-        return AVERROR_EXIT;
+        ret = AVERROR_EXIT;
+        goto error;
     }
 
     ret = ff_decklink_init_device(avctx, avctx->url);
     if (ret < 0)
-        return ret;
+        goto error;
 
     /* Get input device. */
     if (ctx->dl->QueryInterface(IID_IDeckLinkInput, (void **) &ctx->dli) != S_OK) {
@@ -1336,6 +1339,7 @@ av_cold int ff_decklink_read_header(AVFormatContext *avctx)
 
 error:
     ff_decklink_cleanup(avctx);
+    av_freep(&cctx->ctx);
     return ret;
 }