* New "clang-tidy used ... seconds" warnings are reported when
clang-tidy runs for more than 1/2 of TIDY_TIMEOUT seconds.
* Recognize other clang-tidy warnings in separate groups;
they should not be used in normal Android builds.
* Add two more variants of C++ warnings.
Test: warn.py --url=http://cs/android --separator='?l=' build.log > warnings.html
Test: warn.py --gencsv build.log > warnings.csv
Change-Id: I4a2e1c3c817c586cfe3da125b920cca77fcc63b6
f36e01de61