IAR: Fix detection of modern C++ version
!6921 (merged) broke the detection of C++ version because the IN_LIST
operator cannot work directly on a list but requires a variable.
Backport: release
Topic-rename: iar-cmp0057
!6921 (merged) broke the detection of C++ version because the IN_LIST
operator cannot work directly on a list but requires a variable.
Backport: release
Topic-rename: iar-cmp0057