LU-9897 build: use pkgconf for detecting libblkid

LU-9897 build: use pkgconf for detecting libblkid

Currently we have extra complexity to determine where packages are
installed. This approach is also fragile if packages are not
installed in the standard location. This can be handled in a much
cleaner way with pkgconfig. Use pkgconf to discover libblkid.

Test-Parameters: trivial

Change-Id: I5241c2c38b1114d8f061ee5f2a4cb0c677ce2c71
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/35531
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Nathaniel Clark <nclark@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>