When a file is opened with a wrong case, it can work on the developer system but break on a user system with a case-sensitive filesystem.
This will display a warning when it happens.
CAVEATS: It will also display the warning if a symlink is in the path.
Adapt warning if the file is a symlink. Avoid warning on symlinks.
Fix memory leak and avoid `lstat` usage.
Avoid exposing real_path when not in TOOLS_ENABLED mode.
c09731c413