global: remove unnecessary includes from headers.

Each header should only include the other headers it needs to compile;
`devtools/reduce-includes.sh */*.h` does this.  The C files then need
additional includes if they don't compile.

And remove the entirely useless wire/onion_wire.h, which only serves to include wire/onion_wiregen.h.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/xpay/xpay.c

@@ -9,6 +9,7 @@
 #include <common/bolt12.h>
 #include <common/daemon.h>
 #include <common/dijkstra.h>
+#include <common/features.h>
 #include <common/gossmap.h>
 #include <common/gossmods_listpeerchannels.h>
 #include <common/json_param.h>
@@ -20,6 +21,7 @@
 #include <common/route.h>
 #include <common/wireaddr.h>
 #include <errno.h>
+#include <inttypes.h>
 #include <plugins/libplugin.h>
 #include <stdarg.h>