Use final classes.

Author: asfernandes

src/common/ipc/IpcNamedSignal.h

@@ -45,7 +45,7 @@ namespace Firebird {
 
 
 // An event in Windows, a semaphore in POSIX.
-class IpcNamedSignal
+class IpcNamedSignal final
 {
 public:
 	explicit IpcNamedSignal(const string& name);

src/common/ipc/IpcSharedSignal.h

@@ -42,7 +42,7 @@
 namespace Firebird {
 
 
-class IpcSharedSignal
+class IpcSharedSignal final
 {
 public:
 	explicit IpcSharedSignal();