The pledge.com command now supports the new [WIP] unveil() support. For
example, to strongly sandbox our command for listing directories.
o//tool/build/assimilate.com o//examples/ls.com
pledge.com -v /etc -p 'stdio rpath' o//examples/ls.com /etc
This file system sandboxing is going to be perfect for us, because APE
binaries are self-contained static executables that really don't use the
filesystem that much. On the other hand, with non-static executables,
sandboxing is going to be more difficult. For example, here's how to
sandbox the `ls` command on the latest Alpine:
pledge.com -v rx:/lib -v /usr/lib -v /etc -p 'stdio rpath exec' ls /etc
This change fixes the `execpromises` API with pledge().
This change also adds unix.unveil() to redbean.
Fixes#494
