Rendering Engine: integrate font rendering engine

Changes in core/jni/android/graphics/ are related to the text
metrics measurements that are used for text layout modules.
The hardware accelerator uses the rendering engine separately.
Modifications in libs/hwui/ enable the hardware accelerator
to use the 3rd party's rendering engine.

(cherry picked from commit 0101fdb858a5c9ac9be49cdb839fb31b2b29e838)

Conflicts:
    data/fonts/fonts.mk

Change-Id: I22e927209c3e27b8c70651c139bc7521cf28cdf5