Some ibnd_* manpages source other manpages from a `man3/` directory when it
should reference the pages in the current directory.
Instead of modifying contributing sources and using `.so` (discouraged by
mandoc(1)) use MLINKS in the proper Makefile and do not install the affected
manpages.
PR: 237693
Reported by: wosch@FreeBSD.org
Reviewed by: gbe@ (mentor) yuripv@
Approved by: gbe@ (mentor) yuripv@
Differential Revision: https://reviews.freebsd.org/D28727