I'm not sure if the old behavior was intentional, but it was checking
that the glyph flags were a subset of the reference buffer's glyph
flags. I don't see why that is useful. Fix that.
Then make the buffer-verify code ignore flag differences when verifying
buffers, since our unsafe-to-concat flag at least, is conservative and
not guaranteed to be produced the same in fragments. See:
https://github.com/harfbuzz/harfbuzz/issues/3888
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../src/hb-buffer.hh:60:1 in
failure on clusterfuzz-testcase-minimized-hb-subset-get-codepoints-fuzzer-5736539338833920
Behdad Esfahbod