When the match finds a surrogate pair as the first true Unicode character,
then we need to skip both code units of the pair in order to restart the
search. PCRE2 does not allow us to search for individual UTF-16 code
units.
That actually means that counting "." gives us the count of Unicode
characters.
Fixes: QTBUG-110586
Pick-to: 5.15 6.2 6.4 6.5
Change-Id: I194d0a32c94148f398e6fffd173d5b5be8137e19
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
b22ae069ac