[4.5, patch, fortran] Implement DEFERRED bindings

[Tobias Burnus]

Daniel Kraft wrote:
> There's my contribution for gfortran 4.5 patches :D This implements
> DEFERRED bindings for gfortran based on my type-bound procedures
> and ABSTRACT derived-types implementation.
[...]
> No regressions on GNU/Linux-x86-32. Ok for 4.5?

OK.

 * * *

On IRC we discussed whether

  type%abstractType%i = 5
  call type%abstractType%type_bound_proc(5) ! esp. deferred proc

is allowed or not. NAG does not allow it and in Note 4.50 one finds:
"The dynamic type of an object cannot be abstract; therefore, a
 deferred binding cannot be invoked." 

However, this is only a note. I had trouble of pinpointing it in the
standard (incl. corrigenda 1 to 3). I was wondering whether it should
be in the component access section (e.g. C611) or in the inheritance
section.

Tobias