boardd: update cython syntax (#29031)

selfdrive/boardd/boardd_api_impl.pyx

@@ -4,13 +4,15 @@ from libcpp.vector cimport vector
 from libcpp.string cimport string
 from libcpp cimport bool
 
-cdef struct can_frame:
-  long address
-  string dat
-  long busTime
-  long src
+cdef extern from "panda.h":
+  cdef struct can_frame:
+    long address
+    string dat
+    long busTime
+    long src
 
-cdef extern void can_list_to_can_capnp_cpp(const vector[can_frame] &can_list, string &out, bool sendCan, bool valid)
+cdef extern from "can_list_to_can_capnp.cc":
+  void can_list_to_can_capnp_cpp(const vector[can_frame] &can_list, string &out, bool sendCan, bool valid)
 
 def can_list_to_can_capnp(can_msgs, msgtype='can', valid=True):
   cdef vector[can_frame] can_list

selfdrive/boardd/can_list_to_can_capnp.cc

@@ -1,8 +1,6 @@
 #include "cereal/messaging/messaging.h"
 #include "panda.h"
 
-extern "C" {
-
 void can_list_to_can_capnp_cpp(const std::vector<can_frame> &can_list, std::string &out, bool sendCan, bool valid) {
   MessageBuilder msg;
   auto event = msg.initEvent(valid);
@@ -21,5 +19,3 @@ void can_list_to_can_capnp_cpp(const std::vector<can_frame> &can_list, std::stri
   kj::ArrayOutputStream output_stream(kj::ArrayPtr<capnp::byte>((unsigned char *)out.data(), msg_size));
   capnp::writeMessage(output_stream, msg);
 }
-
-}