base,cpu,dev,sim: Pull common logic into ListenSocket::listen().

Create a version of listen() which handles common logic internally,
including scanning for an available port number, and notifying what
port was chosen.

The port is managed internal to ListenSocket, so that the logic
interacting with it doesn't need to manually manage a port number, and
hence a port number does not need to exist for non AF_INET sockets.

Change-Id: Ie371eccc4d0da5e7b90714508e4cb72fb0091875
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69160
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Yu-hsin Wang <yuhsingw@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>

src/cpu/nativetrace.cc

@@ -39,17 +39,13 @@ namespace gem5
 namespace trace {
 
 NativeTrace::NativeTrace(const Params &p)
-    : ExeTracer(p)
+    : ExeTracer(p), native_listener(p.name, 8000)
 {
     if (ListenSocket::allDisabled())
         fatal("All listeners are disabled!");
 
-    int port = 8000;
-    while (!native_listener.listen(port)) {
-        DPRINTF(GDBMisc, "Can't bind port %d\n", port);
-        port++;
-    }
-    ccprintf(std::cerr, "Listening for native process on port %d\n", port);
+    native_listener.listen();
+
     fd = native_listener.accept();
 }