pool allocator no end of trouble, and doesn't make a lot of sense anyway. This
does not solve the problem with mutually recursive functions, but they are much less common.
llvm-svn: 9828
* Separate the policy decisions into a derived class [InlineSimple]
* Move the inlining mechanics into a base class [Inliner]
* Change the inliner to be an SCCPass, making it more structured and
eventually pipelinable with other SCC passes
llvm-svn: 8257