profiling a self compile

[Henry Cejtin]

I don't see how it could be explained by the GC.  Here is what is going on in
the profiling C code.  It charges time to `unknown' iff the  program  counter
is  pointing  at  a  location  which  is  not  in  the  code  loaded from the
executable.   This  means  it  is  in  some  code  in  shared  libraries  (or
dynamically  generated  code,  which we don't have).  I might goose prof.c to
keep track of where it is to see if I can trace it down.