Fixes https://github.com/harfbuzz/harfbuzz/issues/746

Fixes https://github.com/harfbuzz/harfbuzz/issues/1189

Fixes https://github.com/harfbuzz/harfbuzz/issues/1208

Missing "out" indicator. Affect gobject introspection.

The only Indic CM is U+0A75 GURMUKHI SIGN YAKASH, which Uniscribe doesn't treat
specially, and font designers design for that.  So, do the same.

Fixes https://github.com/harfbuzz/harfbuzz/issues/667

Based on experimenting with Uniscribe to extract grammar and categories.

Failures down from 44 to 35:

KHMER: 299089 out of 299124 tests passed. 35 failed (0.0117008%)

We still don't enforce the one-matra rule pre-decomposition, but enforce
an order and one-matra-per-position post-decomposition.

https://github.com/harfbuzz/harfbuzz/issues/667

Fixes https://github.com/harfbuzz/harfbuzz/issues/746

These are only relevant to Sinhala, because they decompose in other
cases.  The USE spec categorizes them all as VPst.  No idea why we
weren't following that before.

Was getting stuck not making progress somehow.

If key_bits+value_bits-cache_bits==32 then -1 is ambiguous...

* Raise error on warnings on -everything
* Enable fontconfig to two bots
* Fix msan bot now that all of its real complain are gone

This reverts commit 247756a7.

Was wrong.  Right fix coming.

Fixes https://github.com/harfbuzz/harfbuzz/issues/504

Also discovered by msan bot.

  GEN      hb-gobject-enums.h
WARNING: Failed to parse "/*< private >*/" in ../../src/hb-buffer.h