The r16-8143-g62dec39dbd6724 change to bits/fs_path.h is also needed for
the corresponding functions in experimental/bits/fs_path.h.
libstdc++-v3/ChangeLog:
* include/experimental/bits/fs_path.h (path::stem)
(path::extension, path::has_stem, path::has_extension): Uglify
ext variable name.