[PATCH 07/79] [Backport to 15] Translate llvm.loop.unroll.full metadata (#1673)

[PATCH 07/79] [Backport to 15] Translate llvm.loop.unroll.full metadata (#1673)

It can be generated via #pragma clang unroll(full) pragma.
llvm.loop.unroll.full means attempt to do full unroll of the
loop and disable the unrolling if the trip count is not known
at compile time.

Unroll mask to which it was previously mapped doesn't much the
description.

The way the patch represents it in SPIR-V is:
 Unroll mask + PartialCount mask with '1' parameter

This patch also removes some overtesting for unroll metadata.

This backports: https://github.com/KhronosGroup/SPIRV-LLVM-Translator/pull/1664

Signed-off-by: Sidorov, Dmitry <dmitry.sidorov@intel.com>
Gbp-Pq: Name 0007-Backport-to-15-Translate-llvm.loop.unroll.full-metad.patch