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/lib/Transforms/IPO/Inliner.cpp b/llvm/lib/Transforms/IPO/Inliner.cpp
index ceaa214..5e05398 100644
--- a/llvm/lib/Transforms/IPO/Inliner.cpp
+++ b/llvm/lib/Transforms/IPO/Inliner.cpp
@@ -72,8 +72,7 @@
     cl::values(clEnumValN(InlinerFunctionImportStatsOpts::Basic, "basic",
                           "basic statistics"),
                clEnumValN(InlinerFunctionImportStatsOpts::Verbose, "verbose",
-                          "printing of statistics for each inlined function"),
-               clEnumValEnd),
+                          "printing of statistics for each inlined function")),
     cl::Hidden, cl::desc("Enable inliner stats for imported functions"));
 } // namespace