This change also fixes a bug with gettid() being incorrect after fork().
We now implement the ENOENT behavior for getauxval(). The getuid() etc.
system calls are now faster too. Plus issetugid() will work on BSDs.
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
