build: make GLUSTERD_WORKDIR rely on localstatedir

- Break-way from '/var/lib/glusterd' hard-coded previously,
  instead rely on 'configure' value from 'localstatedir'
- Provide 's/lib/db' as default working directory for gluster
  management daemon for BSD and Darwin based installations
- loff_t is really off_t on Darwin
- fix-off the warnings generated by clang on FreeBSD/Darwin
- Now 'tests/*' use GLUSTERD_WORKDIR a common variable for all
  platforms.
- Define proper environment for running tests, define correct PATH
  and LD_LIBRARY_PATH when running tests, so that the desired version
  of glusterfs is used, regardless where it is installed.
  (Thanks to manu@netbsd.org for this additional work)

Change-Id: I2339a0d9275de5939ccad3e52b535598064a35e7
BUG: 1111774
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Signed-off-by: Emmanuel Dreyfus <manu@netbsd.org>
Reviewed-on: http://review.gluster.org/8246
Tested-by: Gluster Build System <jenkins@build.gluster.com>