- don't require "OPENCV_PYTHON{2,3}_INSTALL_PATH" if OPENCV_SKIP_PYTHON_LOADER=ON
- avoid unnecessary relative paths in generated config-X.Y.py

Reduce input size for OpenPose tests

introduced by commit 4e629000

  - add infrastructure support for Power9/VSX3
  - fix missing VSX flags on GCC4.9 and CLANG4(#13210, #13222)
  - fix disable VSX optimzation on GCC by using flag ENABLE_VSX
  - flag ENABLE_VSX is deprecated now, use CPU_BASELINE, CPU_DISPATCH instead
  - add VSX3 to arithmetic dispatchable flags

OpenCV 3.4.4

OpenCV 3.4.4

* samples: rename starter_imagelist.cpp

* samples: rename intelperc_capture.cpp => videocapture_intelperc.cpp

* samples: rename openni_capture.cpp => videocapture_openni.cpp

* samples: rename image_sequence.cpp => videocapture_image_sequence.cpp

* samples: rename gstreamer_pipeline.cpp => videocapture_gstreamer_pipeline.cpp

* samples: rename autofocus.cpp => videocapture_gphoto2_autofocus.cpp

* samples: rename live_detect_qrcode.cpp => qrcode.cpp

* Add support for ConvTranspose when parsing ONNX.

* Add support for ConvTranspose when parsing ONNX.

* Add test for Deconvolution