Fixed various errors/warnings reported by cppcheck:

* memory leaks
* resource leaks
* added const's to getters
* removed a few reundant conditions


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35433 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/app/LinkReceiver.h

@@ -27,7 +27,7 @@ class LinkReceiver {
 		virtual ~LinkReceiver(void);
 
 		void SetPort(port_id port);
-		port_id	Port(void) { return fReceivePort; }
+		port_id	Port(void) const { return fReceivePort; }
 
 		status_t GetNextMessage(int32& code, bigtime_t timeout = B_INFINITE_TIMEOUT);
 		bool HasMessages() const;

headers/private/app/LinkSender.h

@@ -22,7 +22,7 @@ class LinkSender {
 		virtual ~LinkSender(void);
 
 		void SetPort(port_id port);
-		port_id	Port() { return fPort; }
+		port_id	Port() const { return fPort; }
 
 		status_t StartMessage(int32 code, size_t minSize = 0);
 		void CancelMessage(void);

headers/private/app/MessageUtils.h

@@ -77,10 +77,10 @@ public:
 								throw fError;
 							}
 
-		status_t			Status() { return fError >= B_OK ? B_OK : fError; };
+		status_t			Status() const { return fError >= B_OK ? B_OK : fError; };
 
 		void				SetSwap(bool yesNo) { fSwap = yesNo; };
-		bool				IsSwapping() { return fSwap; };
+		bool				IsSwapping() const { return fSwap; };
 
 private:
 		BDataIO				*fStream;