Merging r284110:

------------------------------------------------------------------------
r284110 | abataev | 2016-10-13 09:52:46 +0000 (Thu, 13 Oct 2016) | 9 lines

Fix for PR30639: CGDebugInfo Null dereference with OpenMP array
access, by Erich Keane

OpenMP creates a variable array type with a a null size-expr. The Debug
generation failed to due to this. This patch corrects the openmp
implementation, updates the tests, and adds a new one for this
condition.

Differential Revision: https://reviews.llvm.org/D25373
------------------------------------------------------------------------

llvm-svn: 286964