qmakemanager: avoid "style of line directive is a GCC extension" warnings

1 job for !97 with preventgcclinedirectiveextensionwarning in 60 minutes and 1 second (queued for 38 minutes and 32 seconds)
detached
Status Job ID Name Coverage
  Build
failed #30848
linux kf5-qt5 qt5.12

01:00:01

 
Name Stage Failure
failed
linux kf5-qt5 qt5.12 Build The script exceeded the maximum execution time set for the job
Unregistering type class 4
Unregistering type class 3
Unregistering type class 6
Unregistering type class 5
Unregistering type class 2

Start 79: test_gdbprinters
Pulling docker image gitlab/gitlab-runner-helper:x86_64-ac8e767a ...
ERROR: Job failed: execution took longer than 1h0m0s seconds