Added support for debugging emacs daemon

[Michael Welsh Duggan]

I was recently in a position where I wanted to run "emacs --daemon"
under gdb.  After a few fumbles, I hit upon the following. I suggest
either adding this or something like this to .gdbinit or mentioning it
in DEBUG:

  # Follow forks until any possible daemonization is over
  set follow-fork-mode child
  tbreak init_signals
  commands
    set follow-fork-mode parent
  end

Mind you, init_signals is only used since it is the first emacs function
called after daemonization currently.  If things were to be moved
around, this snippet would have to change.

-- 
Michael Welsh Duggan
(address@hidden)