autoload option -- defer linking until it is necessary.

compile options to specify whether '_' should be prepended to C symbols.

separate program to massage the executable file --> remove everything
but global symbol definitions.  So that dld_init can be speed up and
use less memory (esp. for programs with large debugging symtab).

higher level interface to the symtab and unlink functions
	call_func (func, args);

add in support to link (mmap) in SunOS 4's shared library.

*maybe* : provide support for multiple symbol tables--kind of like the
idea of "package" as in Lisp.  This allows different package to define
the same global symbol and so on.  But don't know how this should be
intergrate with C's scope rules, or if there is any conflict with
them.  Need to think about this more.
