Revert "Remove devKerning"

This reverts commit c86c5c0144b85d0bc8ec791f9609ee2d4e7d835a.

Reason for revert: 4 of 5

Original change's description:
> Remove devKerning
> 
> Dev kerning is not supported by any scalers. This is
> mostly removed. The remaining fields fRsbDelta and
> fLsbDelta are kept to keep Android compiling.
> 
> Change-Id: If1a9ee9bb599d4e1bdf4b3751ac0c65246350809
> Reviewed-on: https://skia-review.googlesource.com/124921
> Reviewed-by: Ben Wagner <bungeman@google.com>
> Commit-Queue: Herb Derby <herb@google.com>

TBR=bungeman@google.com,herb@google.com,reed@google.com

Change-Id: If865f702868192a1b72cd811baa996dd1282bbce
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/125263
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
23 files changed