The early return for lamda expressions with deduced return types in
Sema::ActOnCapScopeReturnStmt meant that we were not actually perform
the required return type deduction for such lambdas when in a discarded
context.

This PR removes that early return allowing the existing return type
deduction steps to be performed.

Fixes #153884

Fix developed by, and

Co-authored-by: Corentin Jabot <corentinjabot@gmail.com>

This is in preparation of a follow-up change to stop traversing
unreachable blocks.

This is not NFC because of a subtlety of the early_inc. On a test case
like:

```
  scf.if %cond {
    "test.move_after_parent_op"() ({
      "test.any_attr_of_i32_str"() {attr = 0 : i32} : () -> ()
    }) : () -> ()
  }
```

We recursively traverse the nested regions, and process an op when the
region is done (post-order).
We need to pre-increment the iterator before processing an operation in
case it gets deleted. However
we can do this before or after processing the nested region. This
implementation does the latter.

Operations like:

    %add = arith.addi %add, %add : i64

are legal in unreachable code. Unfortunately many patterns would be
unsafe to apply on such IR and can lead to crashes or infinite loops. To
avoid this we can remove unreachable blocks before attempting to apply
patterns.
We may have to do this also whenever the CFG is changed by a pattern, it
is left up for future work right now.

Fixes #153732

We were incorrectly using the TTI::TCK_RecipThroughput cost kind and
ignoring the kind set in the context.

Using hex format allows to better interpret IDs: 
the first digits represent the thread number, the last digits represent
the ID within a thread

The main change is in callback.h: PRIu64 -> PRIx64

The patch also guards RUN/CHECK lines in openmp/runtime/tests/ompt with clang-format on/off comments and clang-formats the directory.

---------

Co-authored-by: Kaloyan Ignatov <kaloyan.ignatov@rwth-aachen.de>

This should allow us to constexpr many avx512 predicated intrinsics where they wrap basic intrinsics that are already constexpr

Fixes #152321