MFC r326776:

MFC r326776:

Pull in r320396 from upstream clang trunk (by Malcolm Parsons):

  [Sema] Fix crash in unused-lambda-capture warning for VLAs

  Summary:
  Clang was crashing when diagnosing an unused-lambda-capture for a VLA
  because From.getVariable() is null for the capture of a VLA bound.
  Warning about the VLA bound capture is not helpful, so only warn for
  the VLA itself.

  Fixes: PR35555
  Reviewers: aaron.ballman, dim, rsmith

  Reviewed By: aaron.ballman, dim

  Subscribers: cfe-commits

  Differential Revision: https://reviews.llvm.org/D41016

This fixes a segfault when building recent audio/zynaddsubfx port
versions.

Reported by:	hps