Replace def/undef of MAVLINK_THIS_XML_HASH with MAVLINK_FILENAME_XML_HASH

generator/mavgen_c.py

@@ -94,8 +94,7 @@ def generate_main_h(directory, xml):
     #error Wrong include order: MAVLINK_${basename_upper}.H MUST NOT BE DIRECTLY USED. Include mavlink.h from the same directory instead or set ALL AND EVERY defines from MAVLINK.H manually accordingly, including the #define MAVLINK_H call.
 #endif
 
-#undef MAVLINK_THIS_XML_HASH
-#define MAVLINK_THIS_XML_HASH ${xml_hash}
+#define MAVLINK_${basename_upper}_XML_HASH ${xml_hash}
 
 #ifdef __cplusplus
 extern "C" {
@@ -148,10 +147,8 @@ ${{message:#include "./mavlink_msg_${name_lower}.h"
 ${{include_list:#include "../${base}/${base}.h"
 }}
 
-#undef MAVLINK_THIS_XML_HASH
-#define MAVLINK_THIS_XML_HASH ${xml_hash}
 
-#if MAVLINK_THIS_XML_HASH == MAVLINK_PRIMARY_XML_HASH
+#if MAVLINK_${basename_upper}_XML_HASH == MAVLINK_PRIMARY_XML_HASH
 # define MAVLINK_MESSAGE_INFO {${message_info_array}}
 # define MAVLINK_MESSAGE_NAMES {${message_name_array}}
 # if MAVLINK_COMMAND_24BIT