Where to put new header file

Hi there-
   I'm working on getting OpenAFS running on AIX 7.3, but have run into an interesting problem and could use a bit of guidance.

   src/rx/AIX/rx_knet.c includes <net/netisr.h>.  However, on AIX 7.3 IBM added an include to <sys/libsysp.h> which they don't ship (it's not listed in bos.content_list).  Here's the relevant section:

...
#ifdef  _KERNEL

#ifdef  _AIX_FULLOSF
#include "kern/queue.h"
#include "kern/thread.h"
#include "kern/sched_prim.h"
#else
#define EVENT_NETISR    0x0726
#include <sys/libsysp.h>        /* remque/insque */
#endif
...

   The only difference from earlier versions of AIX is the #include <sys/libsysp.h>.  As you can see, there's no real way to use macros to escape from it.  However, we don't really need anything in it for OpenAFS, so my proposal would be to just create an empty sys/libsysp.h file within the OpenAFS source tree.  It would only be picked up by AIX 7.3 builds.  I tested this and it allows the compile to continue.  The question though is, where in the tree should such file live?

   I would also welcome alternative suggestions.

Thank you much!

-Ben