Generate message size #defines also for messages defined in multiple files.

Add testcase for the same.

tests/message_sizes/SConscript

@@ -0,0 +1,11 @@
+# Test the generation of message size #defines
+
+Import('env')
+
+incpath = env.Clone()
+incpath.Append(PROTOCPATH = '#message_sizes')
+
+incpath.NanopbProto("messages1")
+incpath.NanopbProto("messages2")
+
+incpath.Program(['dummy.c', 'messages1.pb.c', 'messages2.pb.c'])

tests/message_sizes/dummy.c

@@ -0,0 +1,9 @@
+/* Just test that the file can be compiled successfully. */
+
+#include "messages2.pb.h"
+
+int main()
+{
+    return xmit_size;
+}
+

tests/message_sizes/messages1.proto

@@ -0,0 +1,27 @@
+enum MessageStatus {
+    FAIL = 0;
+    OK = 1;
+};
+
+message MessageInfo {
+   required fixed32 msg_id = 1;
+   optional fixed32 interface_id = 2;
+}
+
+message MessageResponseInfo {
+   required fixed64 interface_id = 1;
+   required fixed32 seq = 2;
+   required fixed32 msg_id = 3;
+}
+
+message MessageHeader {
+   required MessageInfo info = 1;
+   optional MessageResponseInfo response_info = 2;
+   optional MessageResponse response = 3;
+}
+
+message MessageResponse {
+   required MessageStatus status = 1;
+   required fixed32 seq = 2;
+}
+

tests/message_sizes/messages2.proto

@@ -0,0 +1,8 @@
+import 'nanopb.proto';
+import 'messages1.proto';
+
+message xmit {
+   required MessageHeader header = 1;
+   required bytes data = 2 [(nanopb).max_size = 128];
+}
+