autoconf: detect ctf-tools and add ctf to libafs

autoconf: detect ctf-tools and add ctf to libafs

CTF is a reduced form of debug information similar to DWARF and stab. It
describes types and function prototypes. The principal objective of the
format is to shrink the data size as much as possible so that it could
be included in a production environment. MDB, DTrace, and other tools
use CTF debug information to read and display structures correctly.

This commit introduces a new configure option called --with-ctf-tools.
This option can be used to specify an alternative path where the tools
can be found. If the path is not provided, the tools will be searched
in a set of default directories (including $PATH). The CTF debugging
information will only be included if the corresponding --enable-debug /
--enable-debug-kernel is specified.

Note: at the moment, the Solaris kernel module is the only module
benefited by this commit.

Reviewed-on: https://gerrit.openafs.org/12680
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 88cb536f99dc58fdbeb9fa6c47c26774241a0cb6)

Reviewed-on: https://gerrit.openafs.org/12902
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 96ce04c78b5f745424165494c9b76d7ce227eeaa)

Change-Id: I7f95e5eae2af9f5640e7031dccb79b0d6eb3e51d
Reviewed-on: https://gerrit.openafs.org/13083
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>