An oversight in the code kept the algorithm in the GB11 state, even if
the codepoint that is being processed wouldn't allow for that (for
instance a sequence of ExtPic, Ext and Any).
Refactor the code of GB11/GB12/GB13 to deal with code points that break
the sequences (falling back to "normal" handling).
Add some manual tests; interestingly enough, the failing cases are not
covered by Unicode's tests, as we now pass the entire test suite.
Amends a794c5e287.
Fixes: QTBUG-94951
Pick-to: 6.1 5.15
Change-Id: If987d5ccf7c6b13de36d049b1b3d88a3c4b6dd00
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
d48058f197