This make is obivious that a class was not intended to be derived from.
NPM analysis pass can unfortunately not marked as final because they are
derived from a llvm::Checker<T> template internally by the NPM.
Also normalize the use of classes/structs
* NPM passes are structs
* Legacy passes are classes
* structs that have methods and are not a visitor pattern are classes
* structs have public inheritance by default, remove "public" keyword
* Use typedef'ed type instead of inline forward declaration
The new pass manager does not allow adding module passes at the
-polly-position=before-vectorizer extension point. Introduce a
DumpFunctionPass that dumps only current function. In contrast to the
legacy pass manager's -polly-dump-before, each function will be dumped
into its own file. -polly-dump-before-file is still not supported.
The DumpFunctionPass uses llvm::CloneModule to copy the current function
into a new module and then write it into a file.
