User-mode GDB stub improvements - handle fork

Close gdbserver in child processes, so that only one stub tries to talk
to GDB at a time.  Updated from an earlier patch by Paul Brook.

Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6095 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/gdbstub.h b/gdbstub.h
index 1ba7931..4bfd872 100644
--- a/gdbstub.h
+++ b/gdbstub.h
@@ -13,6 +13,7 @@
 int gdb_handlesig (CPUState *, int);
 void gdb_exit(CPUState *, int);
 int gdbserver_start(int);
+void gdbserver_fork(CPUState *);
 #else
 int gdbserver_start(const char *port);
 #endif