Separate OT headers also.

Such that we don't link to libstdc++.

It's not part of the standard and MSVC doesn't like it.  It makes the code
a lot less elegant than it used to be, but I think it should work now.

Thready-safety disabled in that case, until we add support for pthread, etc.
Fun...

Pointed out by Keith Stribley on HarfBuzz list.

Reported by Keith Stribley on HarfBuzz list.

Part of Bug 595539 - Regressions in rendering certain Thai sequences with
OpenType font

Part of Bug 595539 - Regressions in rendering certain Thai sequences with
OpenType font

Fix off-by-one.

Hiss!

Unlike the rest of the memory-mode enum, this one didn't only
describe the access mode of the input memory region.  Remove it.

If someone wants to inhibit duplicating, they can lock the blob
and throw away the key.

Based on mailing list discussion with Carl Worth.