compat/mingw.c: do not warn when failing to get owner

In the case of Git for Windows (say, in a Git Bash window) running in a
Windows Subsystem for Linux (WSL) directory, the GetNamedSecurityInfoW()
call in is_path_owned_By_current_side() returns an error code other than
ERROR_SUCCESS. This is consistent behavior across this boundary.

In these cases, the owner would always be different because the WSL
owner is a different entity than the Windows user.

The change here is to suppress the error message that looks like this:

  error: failed to get owner for '//wsl.localhost/...' (1)

Before this change, this warning happens for every Git command,
regardless of whether the directory is marked with safe.directory.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>

compat/mingw.c

@@ -2707,9 +2707,7 @@ int is_path_owned_by_current_sid(const char *path)
 				    DACL_SECURITY_INFORMATION,
 				    &sid, NULL, NULL, NULL, &descriptor);
 
-	if (err != ERROR_SUCCESS)
+	if (err == ERROR_SUCCESS && sid && IsValidSid(sid)) {
-		error(_("failed to get owner for '%s' (%ld)"), path, err);
-	else if (sid && IsValidSid(sid)) {
 		/* Now, verify that the SID matches the current user's */
 		static PSID current_user_sid;