Remove HandleTagDeclDefinition class declaration

HandleTagDeclDefinition is in fact a function.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196226 91177308-0d34-0410-b5e6-96231b3b80d8
Parse: Fix references to 'if' that meant 'for', 'do', and 'while'

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196229 91177308-0d34-0410-b5e6-96231b3b80d8