Add dependency fallbacks
commit 17f60286
meson: Add fallback for pcre2 and xml2
When building on Windows those 2 dependencies are usually not available,
but Meson can build them as subproject. Simply run 'meson wrap install
pcre2' and 'meson wrap install libxml2'
gtk4 and all its dependencies can also be built as subproject if adding
a gtk4.wrap file. With those gtksourceview and all its deps can fully
build on Windows with MSVC.
commit 300fa5a0
meson: Use a feature option for introspection
This copy the same behaviour as in gtk4 and all its dependencies. It fix
the build for example on Windows where gobject-introspection is not
usually available.