[OpenCL] Check for invalid kernel arguments in array types

Summary:
OpenCL specification forbids use of several types as kernel arguments.
This patch improves existing diagnostic to look through arrays.

Patch by: Andrew Savonichev

Reviewers: Anastasia, yaxunl

Subscribers: yaxunl, Anastasia, cfe-commits

Differential Revision: https://reviews.llvm.org/D49723

llvm-svn: 338427