BTW, DivC gapi perf tests sporadically failed in nightly builds: https://pullrequest.opencv.org/buildbot/builders/master_openvino-opencl-win64 (Jan 24 is the last failed build, 704)

BTW, DivC gapi perf tests sporadically failed in nightly builds: https://pullrequest.opencv.org/buildbot/builders/master_openvino-opencl-win64 (Jan 24 is the last failed build, 704)

@alalek
I checked and found out that only GPU backend's tests failed. But this PR contains changes for Fluid backend only. The fact that the tests failed on my PR is just a coincidence.
GPU backend's test failed because our intern added the AbsExact() function for comparing GPU backend's results of the DivC operation with the OpenCV's results. But results don't have bit exactness. And they don't have to be bit exact in case of the GPU backend.

@alexgiving
Please fix GPU backend's perf test failures.

#21533 (review)

BTW, DivC gapi perf tests sporadically failed in nightly builds: https://pullrequest.opencv.org/buildbot/builders/master_openvino-opencl-win64 (Jan 24 is the last failed build, 704)

@alalek
This PR should fix the issue mentioned above.

Sporadic failures are observed after merge, e.g.:

• https://pullrequest.opencv.org/buildbot/builders/precommit_windows64/builds/32334
• https://pullrequest.opencv.org/buildbot/builders/precommit_linux64/builds/35426

Nightly:

• https://pullrequest.opencv.org/buildbot/builders/master-win64-vc14/builds/11794
• https://pullrequest.opencv.org/buildbot/builders/master_noOCL_noICV-lin32/builds/1708