fifo_vnodeop_opv_desc symbols.
Many filesystems ffs, lfs, ulfs, chfs, ext2fs etc. use fifofs
internally for their fifo vnops. NFS does too, but it also needs
networking anyway. Unfortunately fifofs brings in a lot of the
networking code so that the rumpkernel is not well partition. In
addition the fifo code is rarely used.
The existing hack depended on duplicating the above symbols and
adding minimal functionality for the majority of the the tests
(except the ffs and the puffs one). In these two cases both symbols
were loaded and the symbol sizes clashed which broke the sanitizers.
While this can be fixed with weak symbols and other kinds of
indirection, it is more straight forward to select between the
minimal and the full fifofs implementation by introducing a new
shared library librumpvfs_nofifofs.
Makefiles so that we can make changes to it centrally as needed and have
less mess. Fixes the sun2 build that needs rumpvfs after librump after
the latest changes.