Describe the bug

New warnings appearing when using ROOT in my projects:

/opt/root/include/ROOT/RStringView.hxx: warning: "_MSVC_LANG" is not defined, evaluates to 0 [-Wundef]

after the recent commits on https://github.com/root-project/root/commits/master/core/foundation/inc/ROOT/RStringView.hxx

Expected behavior

No warnings

Setup

1. ROOT git master
2. Ubuntu 20
3. Self-built