Add check exitcode scripts from opsi wiki for a better logline in the opsi logs

sample/All/CLIENT_DATA/check_nullsoft-exitcode.opsiscript

@@ -0,0 +1,29 @@
+;Request ExitCode from last Program
+set $ExitCode$ = getLastExitCode
+ 
+;Modify Loglevel
+setLogLevel = 4
+ 
+;Check ExitCode
+ 
+if ($ExitCode$ = "0")
+	setLogLevel = 5
+	comment "ExitCode = "+$ExitCode$+" Normal execution (no error)"
+	setLogLevel = 4
+endif
+ 
+if ($ExitCode$ = "1")
+	setLogLevel = 5
+	logError "ExitCode = "+$ExitCode$+" Installation aborted by user (cancel button)"
+	isFatalError
+endif
+ 
+if ($ExitCode$ = "2")
+	setLogLevel = 5
+	logError "ExitCode = "+$ExitCode$+" Installation aborted by script"
+	isFatalError
+endif
+ 
+;Modify Loglevel
+	setLogLevel = 6
+