System information (version)

• OpenCV => 4.5.3
• Operating System / Platform => Host: Windows 64 Bit / Target: QNX 7.1
• Compiler => QCC 7.1

Detailed description

Cross-compiling for QNX is not possible due to missing include headers in parallel due to lack of generalization for Unix systems.

Steps to reproduce

Build for any OS non-Linux system such as QNX, which is neither:

defined __linux__ || defined __APPLE__ || defined __GLIBC__ \
    || defined __HAIKU__ || defined __EMSCRIPTEN__ || defined __FreeBSD__ \
    || defined __OpenBSD__

See parallel.cpp.

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues,
  forum.opencv.org, Stack Overflow, etc and have not found solution
• I updated to latest OpenCV version and the issue is still there
• There is reproducer code and related data files: videos, images, onnx, etc