Revert "Misleading unicode identifier detection pass"

This reverts commit 7f92a1a8.

It triggers an assert, see http://45.33.8.238/linux/60293/step_9.txt

"AST/Decl.h:277: llvm::StringRef clang::NamedDecl::getName() const: Assertion `Name.isIdentifier() && "Name is not a simple identifier"' failed."