Fixes #1054.

Following to https://ci.appveyor.com/project/harfbuzz/harfbuzz/build/1.0.1693/job/mfkjdhcdykjuqdfc

Followup to https://github.com/harfbuzz/harfbuzz/pull/1053

New API:
+hb_set_is_subset()

Part of https://github.com/harfbuzz/harfbuzz/issues/630

This was causing problem on systems without visibility when map was used
from both libharfbuzz and libharfbuzz-subset. Sigh.

https://ci.appveyor.com/project/harfbuzz/harfbuzz/build/1.0.1669/job/dey47nmff0770vp3

Consonant_Initial_Postfixed was split off of Consonant_Succeeding_Repha,
so it should correspond to the same USE class, CONS_FINAL.

https://github.com/grigorig/ucdn/issues/19

UCDN is not updated yet.

Test suite results are unchanged (34).

I should've rebased #1002 before the merge, my bad

Simply, it returns the number of faces on a font blob.

To be used on hb-sanitizer tool but other clients also
can benefit from it.

Apparently this changed between Win 7 and Win 10.

Fixes https://github.com/harfbuzz/harfbuzz/issues/967

To be continued in https://github.com/harfbuzz/harfbuzz/issues/1044

as those might not match what FontTools think of the glyphs if font
does NOT have glyph names.

Some of the build bots, still fail on this.  I suppose mine pass because
I enable C++11...

Anyway, remove these again.

Ouch!

Sigh.

[subset] Have the subset fuzzer pull the text string to subset to from the end of the fuzzer provided data.