Trying to fix kill bug

Author: diegoperini

FFmpegAndroid/src/main/java/com/github/hiteshsondhi88/libffmpeg/FFmpegExecuteAsyncTask.java

@@ -91,6 +91,7 @@ private void checkAndUpdateProcess() throws TimeoutException, InterruptedExcepti
                 while ((line = reader.readLine()) != null) {
                     if (isCancelled()) {
                         process.destroy();
+                        process.waitFor();
                         return;
                     }