Missing includes in legacy cpp interface

Author: Matt Woodward

c/include/libsbp/legacy/cpp/frame_handler.h

@@ -18,6 +18,7 @@
 #include <cstddef>
 
 #include <libsbp/cpp/state.h>
+#include <libsbp/legacy/compat.h>
 #include <libsbp/legacy/cpp/message_traits.h>
 
 SBP_MESSAGE("The legacy libsbp API is deprecated and soon to be removed. All "

c/include/libsbp/legacy/cpp/payload_handler.h

@@ -17,6 +17,7 @@
 #include <array>
 
 #include <libsbp/legacy/cpp/legacy_state.h>
+#include <libsbp/legacy/compat.h>
 #include <libsbp/legacy/cpp/message_traits.h>
 
 SBP_MESSAGE("The legacy libsbp API is deprecated and soon to be removed. All "