Adding option for pin behaviour

[tesonep]

When pinning young objects, the objects are clonned into the old space.
It tries to allocate the object in a segment with already pinned objects.
Avoid the clonning process avoid this search and allocate the clonned object anywhere?

[akgrant43]

I think the comments in SpurMemoryManager>>pinObject: need to be updated to reflect the modified behaviour, e.g.:

pinObject: objOop
    "Attempt to pin objOop, which must not be immediate.
     If the attempt succeeds answer objOop's (possibly moved) oop.
     If the attempt fails, which can only occur if there is no memory, answer 0."
    <inline: false>
    | oldClone seg |
    <var: #seg type: #'SpurSegmentInfo *'>
    self assert: (self isNonImmediate: objOop).
    "If the object is already old and is:
    - large, or
    - already in a old space segment containing other pinned objects, or
    - no other old space segment contains pinned objects
    then just pin the object."
    (memoryMap isOldObject: objOop) ifTrue:
        [(self numBytesOf: objOop) > (1024 * 1024) ifTrue:
            [self setIsPinnedOf: objOop to: true.
             ^objOop].
         seg := segmentManager segmentContainingObj: objOop.
         seg containsPinned ifTrue:
            [self setIsPinnedOf: objOop to: true.
             ^objOop].
         segmentManager someSegmentContainsPinned ifFalse:
            [self setIsPinnedOf: objOop to: true.
             seg containsPinned: true.
             ^objOop]].
    "Otherwise ensure the object is in old space and defer the decision whether to group pinned objects together"
    oldClone := self cloneInOldSpace: objOop forPinning: true.
    oldClone ~= 0 ifTrue:
        [becomeEffectsFlags := self becomeEffectFlagsFor: objOop.
         self setIsPinnedOf: oldClone to: true.
         self forward: objOop to: oldClone.
         self followSpecialObjectsOop.
         coInterpreter postBecomeAction: becomeEffectsFlags.
         self postBecomeScanClassTable: becomeEffectsFlags.
         becomeEffectsFlags := 0].
    ^oldClone 
    ```