CMakeLists - Updates and cleanup (#483)

* CMakeLists - Updates and cleanup

* CTest - CXX Compiler Updates

* Package - Remove FFMPEG exe deps

* CMakeLists - Updates and cleanup

* CTest - CXX Compiler Updates

* Package - Remove FFMPEG exe deps

* FFMPEG - Updates

samples/videoDecodeBatch/README.md

@@ -13,7 +13,7 @@ If the number of files is lesser than the number of threads requested by the use
     * On `Ubuntu`
 
   ```shell
-  sudo apt install ffmpeg libavcodec-dev libavformat-dev libavutil-dev
+  sudo apt install libavcodec-dev libavformat-dev libavutil-dev
   ```
   
     * On `RHEL`/`SLES` - install ffmpeg development packages manually or use [rocDecode-setup.py](../../rocDecode-setup.py) script