This is a complete mess, but

build heap.so, and LD_PRELOAD it.

The wrapped calls to malloc, etc, will check that things haven't been
freed, and do some integrity checking on the blocks.

The program will always dump core on exit if hdmp.so is preloaded. This
is intentional. The hdmp executable can then grovel around he core file
to print leaked memory, etc. You can also attach to the core with gdb,
and use it in conjunction with the hdmp output.

Grep for HDMP_ to see how environment variables affect
things. HDMP_STACKDEPTH is useful.

Currently needs frame-pointer based stack unwinding, so is not useful
on x86_64