spread 'const' love to some variables. this considerably reduces the amount of dirty data around.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@91002 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/LangStandards.cpp b/lib/Frontend/LangStandards.cpp
index 771a58c..08fd932 100644
--- a/lib/Frontend/LangStandards.cpp
+++ b/lib/Frontend/LangStandards.cpp
@@ -14,7 +14,7 @@
 using namespace clang::frontend;
 
 #define LANGSTANDARD(id, name, desc, features) \
-  static LangStandard Lang_##id = { name, desc, features };
+  static const LangStandard Lang_##id = { name, desc, features };
 #include "clang/Frontend/LangStandards.def"
 
 const LangStandard &LangStandard::getLangStandardForKind(Kind K) {