Handle debugger disconnect and reconnect properly

When connecting the debugger the debugger variable was
being set to true before setting up the dbgMain and other related
function pointers. This caused the idle loop to attempt to call dbgMain
which was still NULL. This change makes sure that debugger isn't
set to true until all function pointers are set and that when disconnecting
the remotePort variable is reset back to 0 so we can reconnect properly.

src/wx/cmdevents.cpp

@@ -1968,14 +1968,14 @@ void MainFrame::GDBBreak()
 
             if (connected) {
                 remotePort = gdbPort;
-                debugger = true;
                 emulating = 1;
                 dbgMain = remoteStubMain;
                 dbgSignal = remoteStubSignal;
                 dbgOutput = remoteOutput;
                 cmd_enable &= ~(CMDEN_NGDB_ANY | CMDEN_NGDB_GBA);
                 cmd_enable |= CMDEN_GDB;
                 enable_menus();
+                debugger = true;
             } else {
                 remoteCleanUp();
             }
@@ -2004,6 +2004,7 @@ EVT_HANDLER_MASK(DebugGDBDisconnect, "Disconnect GDB", CMDEN_GDB)
     dbgMain = NULL;
     dbgSignal = NULL;
     dbgOutput = NULL;
+    remotePort = 0;
     remoteCleanUp();
     cmd_enable &= ~CMDEN_GDB;
     cmd_enable |= CMDEN_NGDB_GBA | CMDEN_NGDB_ANY;