BUG/MEDIUM: contrib/spoa_server: Set FIN flag on agent frames

When communicating over SPOP the AGENT-HELLO, AGENT-DISCONNECT,
and ACK frames must have the FIN flag set.
diff --git a/contrib/spoa_server/spoa.h b/contrib/spoa_server/spoa.h
index e9a7a46..8f912e4 100644
--- a/contrib/spoa_server/spoa.h
+++ b/contrib/spoa_server/spoa.h
@@ -21,6 +21,9 @@
 #define SPOP_VERSION      "2.0"
 #define SPOA_CAPABILITIES ""
 
+/* Flags set on the SPOE frame */
+#define SPOE_FRM_FL_FIN         0x00000001
+
 /* All supported data types */
 enum spoe_data_type {
 	SPOE_DATA_T_NULL = 0,