All of NetBSD, FreeBSD, OpenBSD and DragonFly BSD support `$ORIGIN`,
but the last two require `-z origin` as documented at
https://lekensteyn.nl/rpath.html
The `-z origin` option causes a flag bit to be set and has no effect if
the `RPATH` does not contain expandable tokens.
Add a ``FIND_LIBRARY_USE_LIB32_PATHS`` global property analogous to the
``FIND_LIBRARY_USE_LIB64_PATHS`` property. This helps find commands on
multilib systems that use ``lib32`` directories and either do not have
``lib`` symlinks or point ``lib`` to ``lib64``.
Detect the runtime linker's search path and add to the compile time
linker's search path. This is needed because OpenBSD's static linker
does not search for shared library dependencies in the same places as
the runtime linker.
OpenBSD shared libraries use a ".so.<major>.<minor>" extension and do
not have a symlink with just a ".so" extension. Its "ld" is capable of
finding the library with the best version. This change adds support for
finding such libraries. See issue #3470.
