Fix passing compilation flags in CMake

[bernhardmgruber]

No description provided.

[codecov]

Codecov Report

Merging #470 (2902721) into develop (30cfe97) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #470   +/-   ##
========================================
  Coverage    99.23%   99.23%           
========================================
  Files           59       59           
  Lines         5387     5387           
========================================
  Hits          5346     5346           
  Misses          41       41           

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