[subset] Work around OTS bug with FDSelect format 0
[subset] Work around OTS bug with FDSelect format 0

https://github.com/behdad/ots/commit/a049b98c8852078cf872e6d783ebf8205311bffc
https://github.com/khaledhosny/ots/pull/31

Fixes https://github.com/behdad/fonttools/issues/138

fonttools/fonttools,googlefonts/fonttools