Clean "make" fails because libsolaris.so is not built

[nyh]

I tried to build OSv from scratch (after rm -r build) using the command make and it failed:

  MKBOOTFS build/release.x64/bootfs.bin
strip: 'libsolaris.so': No such file
Failed stripping libsolaris.so. Using original.

I can't figure out what piece of code tried to strip libsolaris.so, or why libsolaris.so wasn't built. I was under the impression that libsolaris.so is a new library we need for ZFS in the kernel. Or is it optional - can we continue to have libsolaris inside the kernel and not a separate shared object?

I looked at the Makefile and figured out that make fs=zfs will make it compile libsolaris.so, so I tried that and make worked. But just make should work too - with some reasonable defaults (and certainly not a mysterios build error). @wkozaczuk can you please help me figure this out?