Add a random C99 comment/reference.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@56800 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDecl.cpp

@@ -562,6 +562,7 @@ bool Sema::CheckInitializerTypes(Expr *&Init, QualType &DeclType) {
     if (StringLiteral *strLiteral = IsStringLiteralInit(Init, DeclType))
       return CheckStringLiteralInit(strLiteral, DeclType);
 
+    // C99 6.7.8p16.
     if (DeclType->isArrayType())
       return Diag(Init->getLocStart(),
                   diag::err_array_init_list_required,