libtinyxml: Drop, no longer used by Open webOS

- This recipe is no longer needed to build webos-image. The dependency
  on it was removed together with the task-webos-core recipe in commit
  70b787bcb78db34c6a7d05b19786cb2e48bbece2.

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Change-Id: I063e0d6f92d264b2f85699f008915b3fd0fd46a3
Reviewed-on: http://g2g.palm.com/1108
Reviewed-by: Herb Kuta <herb.kuta@palm.com>
Tested-by: Herb Kuta <herb.kuta@palm.com>