Remove -Wspellcheck and replace it with a diagnostic option.

Thanks to Richard S. for pointing out that the warning would show up
with -Weverything.

llvm-svn: 177218
diff --git a/clang/lib/Frontend/Warnings.cpp b/clang/lib/Frontend/Warnings.cpp
index 767096a..b7547b9 100644
--- a/clang/lib/Frontend/Warnings.cpp
+++ b/clang/lib/Frontend/Warnings.cpp
@@ -56,6 +56,7 @@
 
   Diags.setElideType(Opts.ElideType);
   Diags.setPrintTemplateTree(Opts.ShowTemplateTree);
+  Diags.setWarnOnSpellCheck(Opts.WarnOnSpellCheck);
   Diags.setShowColors(Opts.ShowColors);
  
   // Handle -ferror-limit