Ensure string is properly terminated.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3113 c046a42c-6fe2-441c-8c8c-71466251a162

gdbstub.c

@@ -1032,6 +1032,7 @@ void gdb_do_syscall(gdb_syscall_complete_cb cb, char *fmt, ...)
             *(p++) = *(fmt++);
         }
     }
+    *p = 0;
     va_end(va);
     put_packet(s, buf);
 #ifdef CONFIG_USER_ONLY