Will rarely be of use in SciTECO, but it's part of the officially merged commit.

* It was failing on OpenSUSE Tumbleweed i586 on OBS,
  resulting in duplicate symbols and build errors.
  This was not reproducible with 32-bit builds on OpenSUSE Tumbleweed x86_64.
* Instead of hoping for a compiler warning to be treated as an error,
  we now use a static assertion with a _Generic expression.
* The scintilla submodule has also been updated since Neil was asking to
  update the documentation as well.

* Scintilla had build problems if ptrdiff_t doesn't alias int if it has the
  same storage size (e.g. on NetBSD 10 (armv6)).
* Unfortunately, Neil Hodgson refused to merge my previous Scintilla patches that
  would have fixed the issue at the core.
  See https://groups.google.com/g/scintilla-interest/c/STAv6LgLyCo
* He only agreed to introducing a separate flag to work around the issue
  (`-DPTRDIFF_DOESNT_ALIAS_INT`).
* In order to continue to support all standard C/C++ conforming platforms
  we therefore need a compile-time check to check for the aliasability
  of ptrdiff_t and int.

Shouldn't change anything functionally, but allows us to more broadly
test the patch (especially via OBS).

* It is even more robust now and does not remove the large document
  optimization.
* And actually while problems were caused on NetBSD 10 on ARMv6,
  this likely wasn't a problem on all NetBSD ports and wasn't
  restricted to NetBSD. At the very least Haiku 32-bit was affected
  as well.

It should be more robust now.
The changes on CellBuffer should be reviewed again, though.

* We can use the new SCI_SCROLLVERTICAL instead of SCI_SETFIRSTVISIBLELINE.
* The upgrade will also ease submitting the NetBSD-support patch.

* It requires a forced refresh on startup (even though that should be the
  default). Otherwise, it wouldn't print the info line correctly.
* Redirect stdin and pass it to newterm() to fix key queuing.
  Probably necessary for supporting ncurses on NetBSD as well.
* Avoid doupdate() if screen is too small: fixes crashes for very
  small windows.
* Updated Scintilla: There were some implicit typing assumptions,
  that are broken by this platform.