blkid: Add support for probing exFAT

 * e2fsprogs can't currently detect exFAT filesystems.
 * Apply patch from GoogleTV to add support.

Change-Id: Ib08bdb1d13e995d133a62539e3bfa0e3a22eeead
Merge branch 'cm-10.2' of git://github.com/CyanogenMod/android_external_e2fsprogs into jb-mv