callbacks to be triggered when memory is about to leave the current
process. The system is designed to allow a variety of interfaces,
hopefully including whole-sale replacement of the memory manager,
ld preload tricks, and hooks into the system memory manager. Since
some of these may or may not be available at runtime and we won't know
until runtime, there is a query funtion to look for availability of
such a setup.
* Added ptmalloc2 memory manager replacement code. Not turned on by
default, can be enabled with --with-memory-manager=ptmalloc2.
Only tested on Linux, not even compiled elsewhere. Do not use
on OS X, or you will never see your process again.
* Added AM_CONDITIONAL for threads test to support ptmalloc2's build
system
This commit was SVN r6790.
