Fix small typo.

This is just a stub for now.

This fixes #139614 on non-clang compilers by moving `__has_warning`
completely inside the `#if defined(__clang__)` block. This prevents a
parse failure from compilers which don't recognize `__has_warning`.

Original description:
Followup to #138741.

This adds the requested macro to silence
`-Wunnecessary-virtual-specifier` when declaring virtual anchor
functions in `final` classes, per [LLVM
policy](https://llvm.org/docs/CodingStandards.html#provide-a-virtual-method-anchor-for-classes-in-headers).

It also cleans up any remaining instances of the warning, allowing us to
stop disabling it when we build LLVM.

This reverts commit 0954c9d487e7cb30673df9f0ac125f71320d2936.

It breaks the build when built with gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04).

Followup to #138741.

This adds the requested macro to silence
`-Wunnecessary-virtual-specifier` when declaring virtual anchor
functions in `final` classes, per [LLVM
policy](https://llvm.org/docs/CodingStandards.html#provide-a-virtual-method-anchor-for-classes-in-headers).

It also cleans up any remaining instances of the warning, allowing us to
stop disabling it when we build LLVM.

We can simplify the code with *Map::try_emplace where we need
default-constructed values while avoding calling constructors when
keys are already present.

Following #137070, this PR adds an initial set of Intel `OffloadArch`
values with corresponding predicates that will be used in SYCL
offloading. More Intel architectures will be added in a future PR.

This patch adds the lowering of teams reductions from the omp dialect to
LLVM-IR. Some minor cleanup was done in clang to remove an unused
parameter.