Always normalize cppcheck trailing newlines

Previous conditional approach wasn't catching all cases. Now we always
normalize both actual and expected output for cppcheck to have exactly
one trailing newline (when non-empty), which should handle Windows
platform differences consistently.

Author: pocc

tests/test_hooks.py

@@ -458,13 +458,14 @@ def run_shell_cmd(cmd_name, files, args, _, target_output, target_retcode):
         # Newer cppcheck versions include a checkers report info line
         if cmd_name == "cppcheck":
             actual = re.sub(rb"\nnofile:0:0: information: Active checkers.*\n+", b"\n", actual)
+            # Windows cppcheck adds extra trailing newlines - normalize both to have exactly one
+            if actual and actual.strip():  # Don't normalize empty output
+                actual = actual.rstrip(b"\n") + b"\n"
+            if target_output and target_output.strip():
+                target_output = target_output.rstrip(b"\n") + b"\n"
         # Windows clang uses return-mismatch instead of return-type
         if cmd_name in ["clang-tidy", "include-what-you-use"]:
             actual = actual.replace(b"clang-diagnostic-return-mismatch", b"clang-diagnostic-return-type")
-        # Normalize trailing newlines for cppcheck on Windows
-        if cmd_name == "cppcheck" and (actual.endswith(b"\n\n") or target_output.endswith(b"\n\n")):
-            actual = actual.rstrip(b"\n") + b"\n"
-            target_output = target_output.rstrip(b"\n") + b"\n"
         retcode = sp_child.returncode
         utils.assert_equal(target_output, actual)
         assert target_retcode == retcode