Part of https://github.com/harfbuzz/harfbuzz/issues/1652

This reverts commit 98f14c4c.

Same as previous commit.

This reverts commit 2e86d509.

I think the setup that caused me to do this is faulty and not hiding inlines.

Painful.  All template methods need to be explicitly hidden :(.

Maybe we should switch to -fvisibility=hidden pragma.

A LOT more to go.

Exposed by:

$ make -j5 CPPFLAGS="-O0" CXXFLAGS=-flto=thin LDFLAGS=-lc++ && ./check-symbols.sh

Exposed by:

$ make CPPFLAGS=-O0

Looks like static methods that do not get inlined end up exported.
We have a lot more.  Need to protect all at some point.  Wish there
was an easier way, like the visibility flag we pass that automatically
hides all inline methods.

Was exposed by check-symbols.sh when compiling on OS X 10.14 with:

$ make CPPFLAGS=-Oz CXXFLAGS=-flto=thin LDFLAGS=-lc++

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Currently linker cannot GC hb-ot-font completely because we install
it on fonts by default.  Don't do that if HB_NO_OT_FONT defined.

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Fixes https://github.com/harfbuzz/harfbuzz/issues/1659

As was hit by the fuzzer.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14032