This reverts commit de0b9a46.
This reverts commit 921f0e6e.

Annnnd, revert.  MSVC doesn't like it.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1255
Fixes https://github.com/harfbuzz/harfbuzz/issues/1252

Hopefully this fits fine with SFINAE with all our compilers.

Fixes https://oss-fuzz.com/v2/testcase-detail/5650286710882304

Fixes https://oss-fuzz.com/v2/testcase-detail/5750379279548416

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10990

Fixes https://github.com/harfbuzz/harfbuzz/issues/537

Fixes https://github.com/harfbuzz/harfbuzz/issues/960

dump-emoji still segfaults.  Needs debugging.

Fixes https://github.com/harfbuzz/harfbuzz/issues/960

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10955

Part of https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10955

Fixes https://github.com/harfbuzz/harfbuzz/issues/1247

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10948

Need to map enum values to numerics since we don't have CoreText headers.

A "&" was missing.  Go back to using pointers that are less error-prone.

out_info might have moved since we copied it's position into local
info var.

Fixes https://bugs.chromium.org/p/chromium/issues/detail?id=894937

New API:
+hb_ot_layout_feature_get_name_ids()
+hb_ot_layout_feature_get_characters()

Actual name-fetching API to come later.

New API:
hb_name_id_t
HB_NAME_ID_INVALID