Don't fix end-of-file in files named like licenses

The unanchored `LICENSE` and `COPYING` alternatives match the
pattern anywhere, and therefore exclude the currently used path
`fuzzing/LICENSE-BSD`.

License files are more likely than other files in this project to
be introduced as symlinks, and less likely to be noticed
immediately if they break. Symlinks can be checked out as regular
files when `core.symlinks` is set to `false`, which is rare outside
of Windows but is the default behavior when unset on Windows.

This exclusion fixes the current problem that end-of-file-fixer
breaks those links by adding a newline character to the end (the
symlinks are checked out broken if that is committed). It also
guards against most future cases involving licenses, though
possibly not all, and not other unrelated cases where symlinks may
be used for other purposes.

Although the pre-commit-hooks repository also provides a
destroyed-symlinks hook that detects the situation of a symlink
that has been replaced by a regular file, this does not add that
hook, because this situation is not inherently a problem. The code
here does not require symlinks to be checked out to work, and
adding that would break significant uses of the repository on
Windows.

Note that this leaves the situation where a license file may be a
symlink to another license file and may thus be checked out as a
regular file containing that file's path. However, it is easy to
understand that situation and manually follow the path. That
differs from the scenario where a symlink is created but broken,
because attempting to open it gives an error, and the error message
is often non-obvious, reporting that a file is not found but giving
the name of the symlink rather than its target.

.pre-commit-config.yaml

@@ -26,7 +26,7 @@ repos:
   rev: v4.6.0
   hooks:
   - id: end-of-file-fixer
-    exclude: ^test/fixtures/
+    exclude: ^test/fixtures/|COPYING|LICENSE
   - id: check-symlinks
   - id: check-toml
   - id: check-yaml