Now that CorrectTypo knows how to correctly search classes for typo
correction candidates, there is no good reason to only replace an
existing CXXScopeSpecifier if it refers to a namespace. While the actual
enablement was a matter of changing a single comparison, the fallout
from enabling the functionality required a lot more code changes
(including my two previous commits).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193020 91177308-0d34-0410-b5e6-96231b3b80d8