Add harfbuzz v6 symbols to hb-subset

[luciancooper]

I believe these symbols (new in harfbuzz v6) should be added to those exported in the hb-subset.symbols file:

hb_subset_input_pin_axis_location hb_subset_input_pin_axis_to_default hb_subset_preprocess

Adding these lines to hb-subset.symbols should do it?

_hb_subset_input_pin_axis_location
_hb_subset_input_pin_axis_to_default
_hb_subset_preprocess

[luciancooper]

Realizing now that these symbols are incompatible with compiling harfbuzz with the -DHB_TINY flag. To make them work this would have to be added to config-override-subset.h:

#undef HB_NO_VAR

In accordance with the README, if this "extends harfbuzzjs in ways that you think others will also benefit from", this can be pursued, otherwise, this issue should be closed?

[khaledhosny]

Yes, this seems like it.

[yisibl]

@luciancooper Do you have plans to submit a PR?