swift234

Unicode trie generator: add tests for the generator itself that use non-default
trie parameters and fix a few bugs

The bugs did not affect correctness of the particular instance of trie created
for grapheme cluster property, because trie parameters that were confused with
each other happened to be equal.

Also, fix a trie size bug: we were creating a trie large enough to store
information for 0x200000 code points, but there are only 0x10ffff.  It saved
only 15 bytes in the grapheme cluster tree, because that extra information was
compressed with some supplementary planes that also had default values.  This
also improved trie generation time by almost 2x.


Swift SVN r19457