Do not lock an SMP hit twice for the same transaction (#1134)

Do not lock an SMP hit twice for the same transaction (#1134)

Before commit 4310f8b, anchorToCache() (known then as anchorCollapsed())
was only called for not-yet-anchored entries. For anchored entries, we
called updateCollapsed(). In that commit, a new anchorToCache() caller
(i.e. allowSharing() after peek()) started calling anchorToCache() for
all entries, but anchorToCache() code was not updated to skip anchoring
of anchored entries, leading to an extra read lock placed on a peek()ed
hit entry. The extra lock prevented the entry slot from being reused for
other entries when the entry was later purged (i.e. marked for removal),
drastically decreasing hit ratio in some environments.

Fixed anchorToCache() no longer anchors anchored entries. To make sure
we covered all callers/cases, especially in patches, we changed the call
parameters, addressing an old code simplification TODO.