For some unknown reason the compilation has started using -std=gnu23,
which breaks the build.
Forcing "-std=gnu89" allows the build to succeed, so let's do that
as a workaround to unblock qt5, while we continue investigation why
this broke.
Task-number: QTQAINFRA-7775
Change-Id: I59a29ab9a20d5b2302d72b1e6fbbe52c7ecd277a
Reviewed-by: Dimitrios Apostolou <jimis@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
97af7f3855