Thread the 'Invalid' out parameter through SourceManager::getSLocEntry() and callees of SourceManager::getSLocEntryByID().

Also add an 'Invalid' check in SourceManager::computeMacroArgsCache().

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@183538 91177308-0d34-0410-b5e6-96231b3b80d8