Cygwin: symlink_native: allow linking to `.` again

In 827743ab76 (Cygwin: symlink_native: allow linking to `..`,
2025-06-20), I fixed linking to `..` (which had inadvertently
targeted an incorrect location prior to that fix), but inadvertently
broke linking to `.` (which would now try to pass the empty string as
`lpTargetFileName` to `CreateSymbolicLinkW()`, failing with an
`ERROR_INVALID_REPARSE_DATA` which would be surfaced as "Permission
denied").

Let's fix this by special-casing an empty string as path as referring to
the current directory.

Note: It is unclear to me why the `winsymlinks:nativestrict` code path
even tries to simplify the symbolic link's target path (e.g. turn an
absolute path into a relative one). As long as it refers to a regular
Win32 file or directory, I would think that even something like
`././c` should have only the slashes converted, not the path
simplified (i.e. `.\.\c` instead of `c`). But that's a larger
discussion, and I would like to have the bug worked around swiftly.

Fixes: 827743ab76 (Cygwin: symlink_native: allow linking to `..`, 2025-06-20)
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

0 files changed, 0 insertions, 0 deletions