Fix for bug 6872613 Need to revert back to a less hacky Arabic Font

Roozbeh provided an updated Arabic system UI font which does positioning
properly (using the GPOS mechanism, which is now fully supported in text
rendering), as opposed to the old workaround of using GSUB combinations.
It contains the following additional fixes:

1. Removed the new glyphs and relevant table fields created by GPOS2GSUB
2. [Kept empty glyphs for ZWSP, ZWNJ, and ZWJ]
3. Fixed a wrong GSUB substitution for Urdu Seven
4. Fixed shaping of U+06C1 HEH GOAL
5. Fixed shaping of U+06BA NOON GHUNNA
6. Removed the Rial ligature from the GSUB table
7. Tightened the Alef-Lam-Lam-Heh ligature in the GSUB table which was
getting triggered too frequently

This change just checks in the above work. I did a sanity-check
verification that Arabic text still renders reasonably in the system UI,
but did not check the above cases carefully.

Change-Id: Ie5fb9fd78d21bbfcd62b86deb327a5a2ae9321c6

Author: raphlinus