This adds in necessary sys/types.h pollution for uintptr_t used in sys/event.h, which according to kqueue(2) on NetBSD isn't necessary.
$FreeBSD$ libnetbsd is a thin compatibility layer intended to allow a limited set of NetBSD software to compile as part of the FreeBSD build with little or no modification. It is built as a static library and not installed for general use. Likewise, its header files are not installed.