OpenCV 4.x+ requires enabled C++11 support ROS2 Foxy

[blakermchale]

Describe the bug
When I build the foxy branch of darknet_ros with CUDA support I get the following errors:

/usr/include/opencv4/opencv2/core/cvdef.h:704:4: error: #error "OpenCV 4.x+ requires enabled C++11 support"
  704 | #  error "OpenCV 4.x+ requires enabled C++11 support"
      |    ^~~~~
/usr/include/opencv4/opencv2/core/cvdef.h:710:10: fatal error: array: No such file or directory
  710 | #include <array>

To Reproduce
Steps to reproduce the behavior:

1. Clone the foxy branch
2. colcon build -DCMAKE_BUILD_TYPE=Release
3. See error

Expected behavior
I expect ROS2 Foxy to compile with CUDA support.

System (please complete the following information):

• OS: Ubuntu 20.04
• ROS version: Foxy
• GPU when relevant: NVIDIA RTX 2080 SUPER

Additional context
I noticed that this problem was fixed for Noetic in #308.

[blakermchale]

Just saw #257 and the discussion at the end that referenced this fork https://github.com/ajaypaul2008/darknet_ros/tree/foxy

[Ar-Ray-code]

Please try to use my fork :) .

[blakermchale]

Thanks! I switched to your branch on the PR you made and it works well!

[Ar-Ray-code]

Please close this.

[blakermchale]

Closed since #319 will fix this once it is merged.