Merge Harfbuzz 1.4.2 from the upstream
Changes from 1.3.2 include Opentype 1.8 (variation font support) amd
Math layout support.
The list of changes between 1.3.2 and 1.4.2 is available at
https://goo.gl/Qhml2Z
Update src/hb-version.h and Android.bp (hb-ot-var.cc and hb-ot-math.cc
added).
No need to update hh files derived from rl files because there's no
change in rl files.
Test: Try Arabic, Hindi UI to see if there's any anomaly.
Bug: 34742506
Change-Id: I0692bf2103f4987204338343851647c1240a5e34
