[Bug target/63651] Lot of failures in obj(c|-c++) with yosemite

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63651

--- Comment #14 from Iain Sandoe <iains at gcc dot gnu.org> ---
Created attachment 34310
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34310&action=edit
Arrange for the instancetype type to be recognised

This makes "instancetype" a synonym for "id".

So, in round terms it should work as expected - however:

(a) there's nothing to prevent the User from using it in the Wrong Place (i.e.
somewhere other than a return type).

(b) there's none of the additional analysis that instancetype allows to provide
greater type security.

So it's part #1 of N that will be needed to implement this part of the
modernisation.

====

NOTE that on my tests we still fail to parse the system headers owing to the
use of blocks (but that's a different, and bigger, problem).