lib/simbricks/pcie,network: avoid empty intro structs

Empty structs are not standard C and sizeof for them in gcc is zero but for c++
is 1.

lib/simbricks/network/proto.h

@@ -34,6 +34,7 @@
 
 /** welcome message sent by network devices to eachother. */
 struct SimbricksProtoNetIntro {
+  uint32_t dummy; /* not used, but need to avoid empty struct for standard C */
 } __attribute__((packed));
 
 /******************************************************************************/

lib/simbricks/pcie/proto.h

@@ -92,6 +92,7 @@ struct SimbricksProtoPcieDevIntro {
 
 /** welcome message sent by host to device */
 struct SimbricksProtoPcieHostIntro {
+  uint32_t dummy; /* not used, but need to avoid empty struct for standard C */
 } __attribute__((packed));
 
 /******************************************************************************/

gem5 @ bc74f6a9

-Subproject commit babd65767a0a7db8e2d386d777b9d87c90b44677
+Subproject commit bc74f6a9b15e0ab1b1e28a5a8a7a305b2af4b4af