[clang] Do not traverse EnumDecl's type in RecursiveASTVisitor

This is inconsistent with the code and comments in
RecursiveASTVisitor.h and is not a correct behavior:

https://github.com/llvm/llvm-project/blob/main/clang/include/clang/AST/RecursiveASTVisitor.h#L1879-L1880

> We shouldn't traverse D->getTypeForDecl(); it's a result of
> declaring the type, not something that was written in the source.

Fixes the failures in 1c2e249f