[OpenCL] Output OpenCL version in diagnostics.

Diagnostics should note version dependent issues by giving
a hint about current version being compiled for.

This patch changes diagnostics of static storage class specifier
and generic type qualifier to specify OpenCL version as well as
converts other diagnostics to match the style.

Patch by Vedran Miletic!

Review: http://reviews.llvm.org/D19780
llvm-svn: 269305