[analyzer] Add debug.DumpCalls, which prints out any CallEvents it sees.

[analyzer] Add debug.DumpCalls, which prints out any CallEvents it sees.

This is probably not so useful yet because it is not path-sensitive, though
it does try to show inlining with indentation.

This also adds a dump() method to CallEvent, which should be useful for
debugging.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160030 91177308-0d34-0410-b5e6-96231b3b80d8