May or may not be used in https://github.com/harfbuzz/harfbuzz/pull/1432

[CFF] fix for oss-fuzz 11657: Charset overrun

[CFF] fix leak: oss-fuzz 11662

* guard against no subr access

* code tweak

* add minimized testcase for oss-fuzz 11670 (Null deference)

Check overrun in Charset1_2::get_glyph

removed assert, fixes https://github.com/harfbuzz/harfbuzz/issues/1443

use double as CFF Number implementation

[aat] Expose hb_aat_layout_has_tracking API

New API:
+hb_aat_layout_has_substitution()
+hb_aat_layout_has_positioning()

Happened after 11d2f49a
since now nClasses is unsigned int...

Fixes spurious warnings like:
Fixes https://github.com/harfbuzz/harfbuzz/issues/1436

This reverts commit eb5ddd32.

Broke tests, badly.  To be investigated and reenabled.

Fixes spurious warnings like:
Fixes https://github.com/harfbuzz/harfbuzz/issues/1436

CFF/CFF2 subsetter

* Use nullptr instead of 0/NULL.

* Update test-name-table.cc