fix debian:jessie compilation issue

Summary: missing `#include <stdexcept>` in densematrix.h causes compilation issues on debian:jessie. This commit fixes this issue.

Reviewed By: EdouardGrave

Differential Revision: D17051629

fbshipit-source-id: 23a6cb07d49d69cebba3f9c7c5a21c23592b15aa

src/densematrix.h

@@ -8,12 +8,13 @@
 
 #pragma once
 
+#include <assert.h>
 #include <cstdint>
 #include <istream>
 #include <ostream>
+#include <stdexcept>
 #include <vector>
 
-#include <assert.h>
 #include "matrix.h"
 #include "real.h"