[gclist] FAQ update

[boehm.PARC@xerox.com]

" How does the collector determine object boundaries in the context of
 a non-gc aware compiler so that the entire object gets marked and
 all pointers in it get followed, and not just part thereof?"

The collector typically implements its own version of malloc, which keeps the
necessary information.  There are other reasons for doing this anyway.  The
collector may use the system-provided malloc to obtain large chunks of memory.

 Hans