[analyzer] Make CallEnter, CallExitBegin, and CallExitEnd not be StmtPoints

These ProgramPoints are used in inlining calls,
and not all calls have associated statements anymore.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160021 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed