[ot] Add TODO re zero-len MultipleSubst sequences
[gsub] Minor shuffling
[gsub] Adjust single-length ligature subst to act like single subst
[indic] Don't reorder reph/pref if ligature was expanded

Normally if you want to, say, conditionally prevent a 'pref', you
would use blocking contextual matching.  Some designers instead
form the 'pref' form, then undo it in context.  To detect that
we now also remember glyphs that went through MultipleSubst.

In the only place that this is used, Uniscribe seems to only care
about the "last" transformation between Ligature and Multiple
substitions.  Ie. if you ligate, expand, and ligate again, it
moves the pref, but if you ligate and expand it doesn't.  That's
why we clear the MULTIPLIED bit when setting LIGATED.

Micro-test added.  Test: U+0D2F,0D4D,0D30 with font from:

[1]
https://code.google.com/a/google.com/p/noto-alpha/issues/detail?id=186#c29
Add missing test file.  Oops
Don't use -mstructure-size-boundary=8 on clang arm

As in building for Android / iPhone.  Only set it if
struct{char} alignment is not 1.

NOT tested on an actual Arm architecture.  Guess we'll know
when this makes it to people's build bots.
Fix commit 3f38c1137b6219a646da141b08463ffa922d4e35

Previous commit was not compiling with clang.
[indic] Minor
[indic] Improve base re-finding

No test numbers change.
[indic] Recover OT_H undergone ligation and multiplication

Sometimes font designers form half/pref/etc consonant forms
unconditionally and then undo that conditionally.  Try to
recover the OT_H classification in those cases.

No test number changes expected.
Fix base-position when 'pref' is NOT formed

If pre-base reordering Ra is NOT formed (or formed and then
broken up), we should consider that Ra as base.  This is
observable when there's a left matra or dotreph that positions
before base.

Now, it might be that we shouldn't do this if the Ra happend
to form a below form.  We can't quite deduce that right now...

Micro test added.  Also at:

https://code.google.com/a/google.com/p/noto-alpha/issues/detail?id=186#c29
[Thai] set the correct general category on Nikhahit when decomposing Sara-Am.
When zeroing mark widths for LTR, also adjust offset...

...so that they overstrike preceding glyph.

https://github.com/behdad/harfbuzz/pull/43
[coretext] Remove unused var
Merge branch 'master' of git://github.com/behdad/harfbuzz