Merge patch series "vfs: add O_EMPTYPATH to openat(2)/openat2(2)"

Jori Koolstra <jkoolstra@xs4all.nl> says:

To get an operable version of an O_PATH file descriptor, it is possible
to use openat(fd, ".", O_DIRECTORY) for directories, but other files
currently require going through open("/proc/<pid>/fd/<nr>"), which
depends on a functioning procfs.

This patch adds the O_EMPTYPATH flag to openat(2)/openat2(2). If passed,
LOOKUP_EMPTY is set at path resolution time.

* patches from https://patch.msgid.link/20260424114611.1678641-1-jkoolstra@xs4all.nl:
  selftest: add tests for O_EMPTYPATH
  vfs: add O_EMPTYPATH to openat(2)/openat2(2)

Link: https://patch.msgid.link/20260424114611.1678641-1-jkoolstra@xs4all.nl
Signed-off-by: Christian Brauner <brauner@kernel.org>