- prevent running code over unsupported/non-tested configurations
- prevent integer div by zero

* dnn: fix unaligned memory access crash on armv7

The getTensorContent function would return a Mat pointing to some
member of a Protobuf-encoded message. Protobuf does not make any
alignment guarantees, which results in a crash on armv7 when loading
models while bit 2 is set in /proc/cpu/alignment (or the relevant
kernel feature for alignment compatibility is disabled). Any read
attempt from the previously unaligned data member would send SIGBUS.

As workaround, this commit makes an aligned copy via existing clone
functionality in getTensorContent. The unsafe copy=false option is
removed. Unfortunately, a rather crude hack in PReLUSubgraph in fact
writes(!) to the Protobuf message. We limit ourselves to fixing the
alignment issues in this commit, and add getTensorContentRefUnaligned
to cover the write case with a safe memcpy. A FIXME marks the issue.

* dnn: reduce amount of .clone() calls

* dnn: update FIXME comment
Co-authored-by: NAlexander Alekhin <alexander.a.alekhin@gmail.com>

features2d: repair SimpleBlobDetector

* features2d: revert code change by PR #19859

Reverted commit 76860933

* features2d: check SimpleBlobDetector parameters consistency

- FFmpeg 3.4.8 (no changes)

* Prefix global javascript functions with sub-namespaces

* js: handle 'namespace_prefix_override', update filtering

- avoid functions override with same name but different namespace
Co-authored-by: NAlexander Alekhin <alexander.a.alekhin@gmail.com>

* improve compatibility for qt 6.

* cmake(highgui): rework Qt dependency support

* cmake(highgui): workaround Qt5Config.cmake "components" bug
Co-authored-by: NAlexander Alekhin <alexander.a.alekhin@gmail.com>

Use the return value of gst_init_check instead of testing the error pointer

Automatically sets the correct OpenCV version in the CMAKE example contained in the build.gradle
file of the Android SDK.

  * sharp Gaussian kernel causes over flow and ends up in blank image

* Add RowVec_8u32f

* Fix build errors in Linux x64 Debug and armeabi-v7a

* Reformat code to make it more clean and conventional

* Optimise with vx_load_expand_q()

This submission is used to improve the performance of the inpaint algorithm for 3 channels images(RGB or BGR).

Reason:
The original algorithm implementation did not consider the cache hits.
The loop of channels is outside the core loop, so the perfmance is not very good.
Moving the channel loop inside the core loop can significantly improve cache hits, thereby improving performance.

Performance:
360P, about >= 30% improvement
iphone8P: 5.52ms -> 3.75ms
iphone6s: 14.04ms -> 9.15ms