ibrdtnd: Fix compilation with uClibc-ng and/or uClibc++

For some reason, several C++ headers are not included. Include them.

Also added const fixes to get it to build with uClibc++.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

net/ibrdtnd/patches/020-uClibc-ng.patch

@@ -0,0 +1,20 @@
+--- a/src/security/SecurityCertificateManager.cpp
++++ b/src/security/SecurityCertificateManager.cpp
+@@ -23,6 +23,7 @@
+ #include "Configuration.h"
+ 
+ #include <cstdlib>
++#include <cstring>
+ 
+ #include <ibrcommon/Logger.h>
+ #include <ibrcommon/ssl/TLSStream.h>
+--- a/src/security/SecurityManager.cpp
++++ b/src/security/SecurityManager.cpp
+@@ -28,6 +28,7 @@
+ #include <ibrdtn/security/PayloadConfidentialBlock.h>
+ #include <ibrdtn/security/ExtensionSecurityBlock.h>
+ #include <ibrcommon/Logger.h>
++#include <cstring>
+ 
+ #ifdef __DEVELOPMENT_ASSERTIONS__
+ #include <cassert>