Log Message:
libidn: update to 1.40.

* Noteworthy changes in release 1.40 (2022-06-20) [stable]

** lib: Bump STRINGPREP_VERSION to 1.40.
It was mistakenly left at 1.38 in the 1.39 release.

* Noteworthy changes in release 1.39 (2022-06-20) [stable]

** lib: Code detecting current locale broken since 1.36.
The code always returned ASCII.  The precise cause is complicated to
track down but likely boils down to the new autotools/gettext
bootstrapping sequence introduced in release 1.36.  Reported by Богдан
Пилипенко <bogdan.pylypenko107@gmail.com>.

** maint: Java JAR archive no longer included in source tarball.

** Minor fixes: typos, makefiles, indentation, gnulib update, etc.