port dld to Decstation.

port to systems that use COFF format.

function to return the name of a symbol given its address.

A "bind-name-to-address" function.  That is, the storage for the
variable has already been allocated by other (non-dld) functions, and
want to enter a symtab entry that points to this location.

handle the problem of I-cache:  When removing/replacing any functions,
the I-cache (if there is one) should be flushed--just in case.

make the N_COMM data block contiguous: put down the offset into the
N_COMM area as the symbol's value in the first pass, eliminate the
linked-list altogether, and add to the symbol's value the starting
address of the N_COMM area when I do the relocation of other symbol
addresses--because I need to go through the nlists during the
relocation phase anyway.

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.
