Remove a no-op 'const' from a by-value return type.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168296 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Driver/Arg.h b/include/clang/Driver/Arg.h
index 3b3829a..b85bcdc 100644
--- a/include/clang/Driver/Arg.h
+++ b/include/clang/Driver/Arg.h
@@ -72,7 +72,7 @@
         const char *Value0, const char *Value1, const Arg *BaseArg = 0);
     ~Arg();
 
-    const Option getOption() const { return Opt; }
+    Option getOption() const { return Opt; }
     StringRef getSpelling() const { return Spelling; }
     unsigned getIndex() const { return Index; }