ined by taking an address inside
GC_init's frame, incrementing it repeatedly
in small steps (decrement if <TT>STACK_GROWS_UP</tt>), and reading the value
at each location.  We remember the value when the first
Segmentation violation or Bus error is signalled, round that
to the nearest plausible page boundary, and use that as the
stack base.
<DT><TT>DYNAMIC_LOADING</tt>
<DD>
Should be defined if <TT>dyn_load.c</tt> has been updated for this
platform and tracing of dynamic library roots is supported.
<DT><TT>