re PR d/87788 (Support D on x86_64-apple-darwin*)

ChangeLog:

2018-10-31  Iain Buclaw  <ibuclaw@gdcproject.org>

	PR bootstrap/87788
	PR d/87799
	* configure: Rebuild.
	* configure.ac: Disable D on systems where it is known not to work.

libphobos/ChangeLog:

2018-10-31  Iain Buclaw  <ibuclaw@gdcproject.org>

	PR bootstrap/87789
	PR d/87818
	PR d/87819
	* configure.tgt: New file.

From-SVN: r265658