Fix three OBE items and improve rsync porttree update option

OBE 1: Rather than individual specify none-ports top level directories,
     just search for all directories starting with a capital letter.
     This captures the relatively new "Keywords" directory

OBE 2: Add /lib to ldconfig paths.  This was added for DragonFly 3.8

OBE 3: Remove NO_STAGE line on make.conf.  It caused poudriere to outright
     break this week.  I don't know why this condition existed.  It looks
     obsolete since a long time

Improvement: Don't use cpdup on porttree-update.  It will sync everything.
Even a single file takes tens of minutes to sync.  Instead, leave cpdup
for the initial "rsync" creation, but then use true rsync for incremental
updates.  This works much better in almost all cases.