Build a version of tcmalloc with extra error checking. The code is taken from gperftools 2.8.1, modified for extra checking and for building as part of CxxUtils. It is built into a separate shared library, so won't have any effect unless that library is explicitly loaded.
Only tested for linux/gcc/x86_64, so for now only build for that platform.
To assist in catching errors like double-frees and overwrites. Adds a --checked-tcmalloc flag to Athena. Have CoreDumpSvc handle SIGABRT as well.