Fixes https://github.com/behdad/harfbuzz/pull/35

On iOS CoreText and CoreGraphics are stand-alone frameworks

Fixes warnings.
https://bugzilla.mozilla.org/show_bug.cgi?id=984081

...to avoid an unused function warning; see mozilla bug https://bugzilla.mozilla.org/show_bug.cgi?id=984081.

Not tested.

This is a higher-priority shaper than default shaper ("ot"), but
only picks up fonts that have AAT "morx"/"mort" table.

Note that for this to work the font face's get_table() implementation
should know how to return the full font blob.

Based on patch from Konstantin Ritt.

Useful for Android / Chrome / etc when ICU is built in the same
library as harfbuzz itself.

Apparently some modern fonts have proper GPOS mark positioning
tables, but undesirable precomposed forms!  See thread
"Hebrew composition to presentation forms" and:

  http://tex.stackexchange.com/questions/156775/having-trouble-with-vowel-positioning-in-ezra-sil-xelatex

Test case: U+fb1d,05d9,05b4

Seems like configure.ac is already able to handle it.

See thread "[HarfBuzz] compilation error of 0.9.26 with MinGW"
started by Werner.

Fixes https://github.com/behdad/harfbuzz/pull/21

Fixes github.com/behdad/harfbuzz/pull/19

The OT shaper supersedes the fallback shaper in every case
and the latter become an extra weight for 99.9% of users.

Fixes https://github.com/behdad/harfbuzz/pull/16

Fixes https://github.com/behdad/harfbuzz/pull/17

I believe Windows 8 disables it, and spec update dated
Jan 2014 also clearly says it's disabled by default:

  http://www.microsoft.com/typography/OpenTypeDev/arabic/intro.htm#features

Tone-mark reordering and improved Old Hangul support

[unicode] Exclude the Jamo Filler characters from Default_Ignorable, as some fonts want these to be visible/spacing glyphs.