fixed linux, enhanced qemu

bsp_linux/main.c

@@ -14,13 +14,15 @@ int ai_family = AF_UNSPEC;
 
 void mission(void);
 
-int get_descriptor_rw() { return 1; }
 
 void done() {
-  printf("done.\n");
   exit(0);
 }
 
+void done_error() {
+  exit(1);
+}
+
 int test_socket();
 
 // TODO link to GCC's personality or make the linux build not use it?