Merge NamespaceSpecifierSet's AddNamespace and AddRecord as they are
essentially the same.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193018 91177308-0d34-0410-b5e6-96231b3b80d8
Be smarter about deciding to add a leading '::' to a
NestedNameSpecifier that replaces an existing specifier.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193019 91177308-0d34-0410-b5e6-96231b3b80d8
Allow CorrectTypo to replace CXXScopeSpecifiers that refer to classes.

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