Move SCEVAffinator member definitions out of class body

Instead of defining the relevant functions inline, we now just keep the
declarations in the class itself. This makes the class declaration a lot
easier to read as all functions can be seen at once. We also use this
opportunity to privatize all functions not used in the public interface of the
class.

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@190841 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format recent change

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@190842 91177308-0d34-0410-b5e6-96231b3b80d8