Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11033

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11060

Closes https://github.com/harfbuzz/harfbuzz/issues/1286

Cygwin fixes and CI build

Fixes test just added.

Reported by Nona while updating Android to HarfBuzz 2.0.0.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1274

SFSNDisplay uses these.  We just apply the default kern without
variations right now.  But at least makes the default kern work.

Cygwin does not seem to have strdup.

Cygwin does not seem to have the later

Re https://github.com/harfbuzz/harfbuzz/issues/1271

This needs reviewing

run-shape-fuzzer-tests.py automatically runs valgrind if see available
but test/api runs it by request, we probably should normalize the approaches
later

Actually the check is right,

On -myanmar.hh, on that particular switch, OT_C is indic_category_t
but OT_D is myanmar_category_t so we are mixing the types in one variable.

And on -arabic.cc, step can goes one number higher than step_t enum in the
loop so we are actually using it as an unsinged int.

Okay, let's see if the gods are happy now...