llvm-undname: More coverage-related cleanups
- The loop in demangleFunctionParameterList() only exits
on Error, @, and Z. All 3 cases were handled, so the
rest of the function is DEMANGLE_UNREACHABLE.
- The loop in demangleTemplateParameterList() always returns
on Error, so there's no need to check for that in the loop
header and after the loop.
- Add test cases for invalid function parameter manglings.
- Add a (redundant) test case for a simple template parameter
list mangling.
- Add a test case pointing out that varargs functions aren't
demangled correctly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@362540
91177308-0d34-0410-b5e6-
96231b3b80d8