PtrValue is already of type Value *.

We just replaced SmallSet<T *, N> with SmallPtrSet<T *, N>, bypassing
the redirection found in SmallSet.h.  With that, we no longer need to
include SmallSet.h in many files.

This patch replaces SmallSet<T *, N> with SmallPtrSet<T *, N>.  Note
that SmallSet.h "redirects" SmallSet to SmallPtrSet for pointer
element types:

  template <typename PointeeType, unsigned N>
class SmallSet<PointeeType*, N> : public SmallPtrSet<PointeeType*, N>
{};

We only have 140 instances that rely on this "redirection", with the
vast majority of them under llvm/. Since relying on the redirection
doesn't improve readability, this patch replaces SmallSet with
SmallPtrSet for pointer element types.

These are identified by misc-include-cleaner.  I've filtered out those
that break builds.  Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.

- Remove calls to pass initialization from pass constructors.
- https://github.com/llvm/llvm-project/issues/111767

Identified with misc-include-cleaner.

This is a helper to avoid writing `getModule()->getDataLayout()`. I
regularly try to use this method only to remember it doesn't exist...

`getModule()->getDataLayout()` is also a common (the most common?)
reason why code has to include the Module.h header.

These are the last remaining "trivial" changes to passes that use
Instruction pointers for insertion. All of this should be NFC, it's just
changing the spelling of how we identify a position.

In one or two locations, I'm also switching uses of getNextNode etc to
using std::next with iterators. This too should be NFC.

---------

Merged by: Stephen Tozer <stephen.tozer@sony.com>

Continuing the patch series to get rid of debug intrinsics [0], instruction
insertion needs to be done with iterators rather than instruction pointers,
so that we can communicate information in the iterator class. This patch
adds an iterator-taking insertBefore method and converts various call sites
to take iterators. These are all sites where such debug-info needs to be
preserved so that a stage2 clang can be built identically; it's likely that
many more will need to be changed in the future.

At this stage, this is just changing the spelling of a few operations,
which will eventually become signifiant once the debug-info bearing
iterator is used.

[0] https://discourse.llvm.org/t/rfc-instruction-api-changes-needed-to-eliminate-debug-intrinsics-from-ir/68939

Differential Revision: https://reviews.llvm.org/D152537