[PM] Update the examples to reflect the removal of the

[PM] Update the examples to reflect the removal of the
llvm/PassManager.h wrapper header and its using declarations. These now
directly use the legacy namespace.

I had updated the #include lines in my large commit but forgot that the
examples weren't being built and didn't update the code to use the
correct namespace. Sorry for the noise here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229095 91177308-0d34-0410-b5e6-96231b3b80d8