Turn cl::values() (for enum) from a vararg function to using C++ variadic template

The core of the change is supposed to be NFC, however it also fixes
what I believe was an undefined behavior when calling:

 va_start(ValueArgs, Desc);

with Desc being a StringRef.

Differential Revision: https://reviews.llvm.org/D25342

llvm-svn: 283671
diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index bbf3679..429df62 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -72,7 +72,7 @@
                    ".debug_str_offsets.dwo"),
         clEnumValN(DIDT_CUIndex, "cu_index", ".debug_cu_index"),
         clEnumValN(DIDT_GdbIndex, "gdb_index", ".gdb_index"),
-        clEnumValN(DIDT_TUIndex, "tu_index", ".debug_tu_index"), clEnumValEnd));
+        clEnumValN(DIDT_TUIndex, "tu_index", ".debug_tu_index")));
 
 static void error(StringRef Filename, std::error_code EC) {
   if (!EC)