Remove LEFontInstance::getFontTable(LETag)

When we fixed the security issue with the getFontTable(LETag):

http://site.icu-project.org/download/51#TOC-Known-Issues

we left existing clients vulnerable until they switched to getFontTable(LETag, size_t&). That was wrong. I wish we had removed getFontTable(LETag) completely such that clients wouldn't compile until they fixed the security issue.

Please do that. Otherwise no one will know how many vulnerabilities will stay unfixed forever. Just finished debugging one bug that came down to a rogue client.

I'm going to remove the single arg version in icu-le-hb, and remove default implementation of the two-arg version.

behdad