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.

Replace it with a forward declaration instead. Analysis.h is pulled in
by all passes, but not all passes need to access the module.

Namespaces are terminated with a closing comment in the majority of the
codebase so do the same here for consistency. Also format code within
some namespaces to make clang-format happy.

Port the legacy CallGraphViewer and CallGraphDOTPrinter to work with the new pass manager.

Addresses issue https://github.com/llvm/llvm-project/issues/54323
Adds back related tests that were removed in commits d53a4e7b4a87 and 9e9d9aba1475

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D122989

Number of lines output by preprocessor:
before: 1065940348
after:  1065307662

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D120659

This reverts commit fe364e5dc78c58a915986d9a44cfd65f919a00c2.

Causes breakages, e.g. https://lab.llvm.org/buildbot/#/builders/188/builds/5266

These were added to prevent functions from being removed by WPO.

But that doesn't make sense, correct WPO will not remove functions we actually use.

I noticed these because compiling cc1_main.cpp was pulling in random LLVM pass headers.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D112971

Stop using the compatibility spellings of `OF_{None,Text,Append}`
left behind by 1f67a3cba9b09636c56e2109d8a35ae96dc15782. A follow-up
will remove them.

Differential Revision: https://reviews.llvm.org/D101650