Add a LangOptions::areExceptionsEnabled and start using it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126062 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDeclCXX.cpp b/lib/CodeGen/CGDeclCXX.cpp
index 8b37e9a..e295267 100644
--- a/lib/CodeGen/CGDeclCXX.cpp
+++ b/lib/CodeGen/CGDeclCXX.cpp
@@ -166,7 +166,7 @@
       Fn->setSection(Section);
   }
 
-  if (!CGM.getLangOptions().Exceptions)
+  if (!CGM.getLangOptions().areExceptionsEnabled())
     Fn->setDoesNotThrow();
 
   return Fn;