Add default dtors to satisfy -Wnon-virtual-dtor

close #1664

include/boost/beast/_experimental/unit_test/suite.hpp

@@ -193,6 +193,10 @@ public:
     {
     }
 
+    virtual ~suite() = default;
+    suite(suite const&) = delete;
+    suite& operator=(suite const&) = delete;
+
     /** Invokes the test using the specified runner.
 
         Data members are set up here instead of the constructor as a

include/boost/beast/core/async_base.hpp

@@ -249,6 +249,10 @@ public:
     /// Move Constructor
     async_base(async_base&& other) = default;
 
+    virtual ~async_base() = default;
+    async_base(async_base const&) = delete;
+    async_base& operator=(async_base const&) = delete;
+
     /** The type of allocator associated with this object.
 
         If a class derived from @ref async_base is a completion