Change indentation of multi-line nested name specifiers.

Before:
aaaaaaaa::
    aaaaaaaa::
    aaaaaaaa();
After:
aaaaaaaa::
    aaaaaaaa::
        aaaaaaaa();

The reason for the change is that:
a) we are not sure which is better
b) it is a really rare edge case
c) it simplifies the code
d) it currently causes problems with memoization

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181421 91177308-0d34-0410-b5e6-96231b3b80d8