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-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 9dbce97..43a9a7a 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -188,8 +188,7 @@
 
 cl::opt<DIDumpType> llvm::DwarfDumpType(
     "dwarf", cl::init(DIDT_Null), cl::desc("Dump of dwarf debug sections:"),
-    cl::values(clEnumValN(DIDT_Frames, "frames", ".debug_frame"),
-               clEnumValEnd));
+    cl::values(clEnumValN(DIDT_Frames, "frames", ".debug_frame")));
 
 cl::opt<bool> PrintSource(
     "source",