tests : fix compilation issues, adding <iostream> and removing
<Eigen/Array>
diff --git a/doc/snippets/compile_snippet.cpp.in b/doc/snippets/compile_snippet.cpp.in
index b0bcb62..5cfcbfe 100644
--- a/doc/snippets/compile_snippet.cpp.in
+++ b/doc/snippets/compile_snippet.cpp.in
@@ -4,6 +4,7 @@
 #include <Eigen/Cholesky>
 #include <Eigen/Geometry>
 #include <Eigen/Jacobi>
+#include <iostream>
 
 using namespace Eigen;
 using namespace std;