Patch #1 of Saem Ghani's Pass Manager refactoring. From the man:

Patch #1 of Saem Ghani's Pass Manager refactoring.  From the man:

"All this should do is create what will eventually be the specialised
passmanagers.  Currently, the templates are inheriting them, once the
template specialisations' methods have been absorbed, patches
submitted method by method.  I'll nuke the specialisations and have
the new objects inherit directly from passmanagert, and sanitise the
world of all references to templates.
"

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25053 91177308-0d34-0410-b5e6-96231b3b80d8