xobjdetect: (5.x) fix to build world with xobjdetect

[Kumataro]

Closed #3861

This patch is to build world module with xobjdetect successfully.

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• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[Kumataro]

Linux 64 test is failed, but it is related cmake version.

https://pullrequest.opencv.org/buildbot/builders/precommit-contrib_linux64/builds/101396/steps/cmake/logs/stdio

 using PTY: False
Re-run cmake no build system arguments
CMake Error at CMakeLists.txt:18 (cmake_minimum_required):
  CMake 3.13 or higher is required.  You are running version 3.10.2


-- Configuring incomplete, errors occurred!
program finished with exit code 1
elapsedTime=0.126756