AdressSanitizer is a lightweight memory error detector that instruments at
compile time instead of at execution time. This allows serious memory
errors to be detected without the cost of slowing down the whole program
that often happens when Valgrind is used. It is also easier to enable for
test runs as it is a simple compiler flag.
This is a cherry-pick of fb9b027842a7b65c4826455cd34d88e2f5f28e79 from the
2.2 branch.