fixed trailing whitespaces
renamed files *vaapi* to *va_intel*
changed names vaapi* to va_intel*

- IPP is disabled by default when compiler is mingw (couldn't make it
work)
- fixed some warnings
- fixed some `__GNUC__` version checks (for correctness and convenience)
- removed UTF-8 BOM from hough.cpp (fixes #5253)

Revert merging of pull request #5176 from vladimir-dudnik:master (reverted from commit 5ee00ec5)

fixed whitespaces
fixed issues
fixed issue
fixed module statement issues
fixed access mode
added initialization check
fixed warning

TLS was redesigned in more straightforward way;
OPENCV_ABI_COMPATIBILITY define was added;

Fix for bug #5007: moved definition of Size_MatDepth_t and Size_MatDepth from ts_perf.hpp to perf_channels.cpp. This way they are closer to where they are needed and live in a different namespace (possibly the reason why the fix works).

add condition to skip unmapping for internally allocated host memory. this should fix map_unmap_counting UMat test.

enabled test UMat copyTo. Now it will detect FAIL on Intel platform for ROI (issue with clEnqueueCopyBufferRect)