bin/misc-functions.sh: normalize ${D%/}${D} slash

This will fix bug #467886.
bin/misc-functions.sh: use pipe for find ${D}${D}
Use non-greedy findConsumers for bug #467896.

This fixes the preserve-libs display and @preserved-rebuild to omit
library consumers that are satisfied by alternative providers.
man/emerge: clarify --rebuild-if-new-slot #467924
Support RESTRICT=preserve-libs, bug #364427

Note than when a package is merged, RESTRICT=preserve-libs applies if
*either* the new instance or the old instance sets
RESTRICT=preserve-libs.

Also note that when the user has preserve-libs enabled, the
--depclean-lib-check option may now kick in if one of the packages
selected for unmerge sets RESTRICT=preserve-libs.
Silence embedded profile warning for bug #467142.
_getMissingProperties: remove || support

PROPERTIES is not allowed to contain ||, according to PMS.
Support ACCEPT_RESTRICT for bug #467622.