Add include_guard to all cmake files

Summary

CMake provides include-guards similar to #pragma once. In order to not include files multiple times and in consequence define/call variables, macros or functions multiple times, all cmake files should be protected.

added 1 commit

• 1da9741c - Add include_guard to all cmake files

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changed milestone to %New CMake Build-System

added buildsystem label

This MR only adds include guards to cmake files. There is no interface change and it should not influence any downstream module. After a rebase I will merge it.

added 40 commits

• 1da9741c...803bd22d - 39 commits from branch master
• 24289ee9 - Add include_guard to all cmake files

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mentioned in commit c36b4c3d

merged