* Eltwise::DIV support in Halide backend

* fix typo

* remove div from generated test suite to pass CI, switching to manual test...

* ensure divisor not near to zero

* use randu

* dnn(test): update test data for Eltwise.Accuracy/DIV layer test

* 3rdparty: update libwebp 1.0.2 => 1.0.3

https://github.com/webmproject/libwebp/releases/tag/v1.0.3

* 3rdparty(libwebp): re-apply patches

* cmake: avoid deprecated LINK_PRIVATE/LINK_PUBLIC

see CMP0023 (CMake 2.8.12+)

* cmake: fix 3rdparty list

- don't include OpenCV modules

Add checks for empty operands in Matrix expressions that don't check properly

* Starting to add checks for empty operands in Matrix expressions that
don't check properly.

* Adding checks and delcarations for checker functions

* Fix signatures and add checks for each class of Matrix Expr operation

* Make it catch the right exception

* Don't expose helper functions to public API

* imgproc: Prevent 1B overrun of 8C3 SIMD optimization

The fourth value read via v_load_q is essentially ignored,
but can cause trouble if it happens to cross page boundaries.

The final few iterations may attempt to read the most extreme
elements of S, which will read 1B beyond the array in most
aligment cases. Dynamically compute the stop. This could be
hoised from the loop, but will require a more extensive change.

Likewise, cleanup the iteration increment statements to make
it more obvious they do channel count (3) elements per pass.

This should resolve #16137

* imgproc(resize): extra check

dnn(eltwise): fix handling of different number of channels

* dnn(test): reproducer for Eltwise layer issue from PR16063

* dnn(eltwise): rework support for inputs with different channels

* dnn(eltwise): get rid of finalize(), variableChannels

* dnn(eltwise): update input sorting by number of channels

- do not swap inputs if number of channels are same after truncation

* dnn(test): skip "shortcut" with batch size 2 on MYRIAD targets

Drop:
- discouraged CMAKE_CL_64
- MSVC64
- MINGW64

-c is required to avoid linking (and the associated missing "main" message)
when linker flags like "-Wl,-z,relro" are passed to GCC

* Add eps error checking for approxPolyDP to allow sensible values only
for epsilon value of Douglas-Peucker algorithm.

* Review changes for PR