prevent address and leak sanitizers from failing under travis-ci's ptrace
prevent address and leak sanitizers from failing under travis-ci's ptrace

Clang’s address sanitizer fails to run under travis-ci with the error:
> ==2508==LeakSanitizer has encountered a fatal error.
> ==2508==HINT: For debugging, try setting environment variable
LSAN_OPTIONS=verbosity=1:log_threads=1
> ==2508==HINT: LeakSanitizer does not work under ptrace (strace, gdb,
etc)

The local machine tests still add the address sanitizer, but the
travis-ci tests avoid it due to this limitation.

boazsegev/facil.io,boazsegev/facil.io