In Windows files, detect CR without LF as well as LF without CR

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/check-files.py b/tests/scripts/check-files.py
index e4a365f..1a9ba30 100755
--- a/tests/scripts/check-files.py
+++ b/tests/scripts/check-files.py
@@ -140,7 +140,7 @@
 
 
 class WindowsLineEndingIssueTracker(LineIssueTracker):
-    """Track files with non-Windows line endings (i.e. files without CR)."""
+    """Track files with non-Windows line endings (i.e. CR or LF not in CRLF)."""
 
     heading = "Non-Windows line endings:"
 
@@ -148,7 +148,7 @@
         return is_windows_file(filepath)
 
     def issue_with_line(self, line, _filepath):
-        return not line.endswith(b"\r\n")
+        return not line.endswith(b"\r\n") or b"\r" in line[:-2]
 
 
 class TrailingWhitespaceIssueTracker(LineIssueTracker):