C++: Add test from issue github#5190.

Author: MathiasVP

cpp/ql/test/library-tests/dataflow/taint-tests/smart_pointer.cpp

@@ -65,4 +65,14 @@ void test_shared_field_member() {
     std::unique_ptr<A> p = std::make_unique<A>(source(), 0);
     sink(p->x); // $ MISSING: ast,ir
     sink(p->y); // not tainted
+}
+
+void getNumber(std::shared_ptr<int> ptr) {
+  *ptr = source();
+}
+
+int test_from_issue_5190() {
+  std::shared_ptr<int> p(new int);
+  getNumber(p);
+  sink(*p); // $ MISSING: ast,ir
 }

cpp/ql/test/library-tests/dataflow/taint-tests/stl.h

@@ -348,7 +348,7 @@ namespace std {
 	class shared_ptr {
 	public:
 		shared_ptr() noexcept;
-		explicit shared_ptr(T*);
+		explicit shared_ptr(T*); shared_ptr(const shared_ptr&) noexcept;
 		template<class U> shared_ptr(const shared_ptr<U>&) noexcept;
 		template<class U> shared_ptr(shared_ptr<U>&&) noexcept;