Fix compiler warnings

Fix base classes without virtual destructors and missing initialisors.

include/internal/catch_capture.hpp

@@ -559,7 +559,8 @@ public:
         const char* expr = "",
         bool isNot = false
     )
-    : m_result( expr, isNot, filename, line, macroName )
+    : m_result( expr, isNot, filename, line, macroName ),
+      m_messageStream()
     {}
     
     ///////////////////////////////////////////////////////////////////////////
@@ -659,7 +660,7 @@ class ScopedInfo
 public:
     ///////////////////////////////////////////////////////////////////////////
     ScopedInfo
-    ()
+    () : m_oss()
     {
         Hub::getResultCapture().pushScopedInfo( this );
     }