* - headers in "infer/" and "infer/ie/" folders are included into gapi_ext_hdrs;
+ because of that a few #includes are required in the headers
- HAVE_INF_ENGINE flag check in headers "infer/ie.hpp" and "infer/ie/util.hpp" is deleted

* - the "ie/util.hpp" header is a private header now as it's used for tests; it's been moved to the scr directory to the place next to the implementation file "ie/giebackend.cpp"
- the path to this header in files "ie/giebackend.cpp" and "test/infer/gapi_infer_ie_test.cpp" is updated
- As it's private header now and explicitly depends on IE, the "HAVE_INF_ENGINE" flag check is returned

   - make static analysis happy

* Support GArray as input in fluid kernels

* Create tests on GArray input in fluid

* Some fixes to fully support GArray

* Refactor code and change the kernel according to review

* Add histogram calculation as a G-API kernel

Add assert that input GArgs in fluid contain at least one GMat

detected by UBSAN

* Fix IE FullyConnected layer

* Fix MyriadX

* Convert lkpyramid from SSE SIMD to HAL - 90% faster on Power (VSX).

* Replace stores with reduce_sum.  Rework to handle endianess correctly.

* Fix compiler warnings by casting values explicitly to shorts

* Switch to CV_SIMD128 compiler definition.  Unroll loop to 8 elements since we've already loaded the data.

Implementation of colormap "Turbo" (#15388)

* implemented turbo colormap

* add colormap image

* changed float value to avoid cast

* sorted flag check alphabetically

* Add debug build option to MacOs and iOS build scripts

* osx: allow selection of MACOSX_DEPLOYMENT_TARGET

* Add --debug_info flag to iOS and macOS builds for building with debug info