When building with zfs, ./configure lets us define specific paths for spl and zfs headers, in addition to spl and zfs object directories:
--with-spl=path
--with-spl-obj
--with-zfs=path
--with-zfs-obj

The problem is there is no equivalent for zfs development headers. In config/lustre-build-zfs.m4, the 'LB_ZFS_USER' configure check looks at /usr/include/libzfs and /usr/include/libspl, and there is no way to specify alternate directories.

It seems a configure option like --with-zfs-devel is missing.