SOLARIS: convert from ancient _depends_on to ELF dependencies

SOLARIS: convert from ancient _depends_on to ELF dependencies

The ancient way of declaring module dependencies with _depends_on has
been deprecated since SunOS 2.6 (circa 1996). The presence of the old
_depends_on symbol triggers a warning message on the console starting
with Solaris 12, and the kernel runtime loader (krtld) feature of using
the _depends_on symbol to load dependencies may be removed in a future
version of Solaris.

Convert the kernel module from the ancient _depends_on method to modern
ELF dependencies.  Remove the old _depends_on symbol and specify the -dy
and -N <name> linker options to set the ELF dependencies at link time,
as recommended in the Solaris device driver developer guidelines [1].

This commit does not change the declared dependencies, which may be
vestiges of ancient afs versions.

[1]: http://docs.oracle.com/cd/E19455-01/805-7378/6j6un037u/index.html#loading-16

Change-Id: Ic5abd82108cd59c0796a8d7659ddaffa791dbeee
Reviewed-on: https://gerrit.openafs.org/12453
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>