autoconf: use include directives instead of recursing down contrib

Also make the pyzfs build actually out-of-tree and quiet by default

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Rapptz <rapptz@gmail.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13316