Do not register signal handlers when building options

src/main/scala/leon/Main.scala

@@ -177,8 +177,6 @@ object Main {
 
     val intManager = new InterruptManager(reporter)
 
-    intManager.registerSignalHandler()
-
     LeonContext(settings = settings,
                 reporter = reporter,
                 files = files,
@@ -215,6 +213,8 @@ object Main {
 
       val ctx = processOptions(args.toList)
 
+      ctx.interruptManager.registerSignalHandler()
+
       ctx.timers.get("Leon Opts") += timer
 
       // Compute leon pipeline