Enable -Wexit-time-destructors for all in-tree library targets and
update process-lifetime library statics so they no longer register
exit-time destructors. Long-lived caches, lookup tables, singleton
registries, and generated constants now use NeverDestroyed or leaked
references where the data is intended to live until process exit.
Update LibWeb, LibLine, and the binding generators so regenerated
sources follow the same rule instead of reintroducing destructed
statics.
Before this commit, LibCore/System.h exposed only part of
System::stat API on Windows. Namely, users of Core::System::stat
had to #include <dirent.h> in order to check the return value of stat.
It is OK for low-level libs like LibCore/LibFileSystem, but
S_ISDIR is also used in LibWeb\Loader\GeneratedPagesLoader.cpp.
We want to avoid platform #ifdefs in LibWeb.
