Add new clang and clang-tidy warning patterns

* New "clang-tidy aborted ..." warnings are reported when
  clang-tidy runs for more than TIDY_TIMEOUT seconds.

Test: warn.py --url=http://cs/android --separator='?l=' build.log > warnings.html
Test: warn.py --gencsv build.log > warnings.csv
Change-Id: Iea62b06b2cf78737d7713dabbcf6d9ac8ba23898

tools/warn/cpp_warn_patterns.py

@@ -93,6 +93,8 @@ warn_patterns = [
          [r".*: warning: Null passed to a callee that requires a non-null"]),
     medium('Unused command line argument',
            [r".*: warning: argument unused during compilation: .+"]),
+    medium('Set but not used',
+           [r".*: warning: .* set but not used.*Wunused-but-set"]),
     medium('Unused parameter',
            [r".*: warning: unused parameter '.*'"]),
     medium('Unused function, variable, label, comparison, etc.',