Fix (unreported) important memory leak in Boolean modifier using a Collection operand and Fast mode.

Code handling repetitive boolean operations when using several objects
from a Collection would not handle result mesh properly, re-creating for
each object without properly freeing it.

Further more, existing code was effectively converting the BMesh to mesh
twice, including a modification of the initial (input) mesh, which
modifiers should never do!

Removed the extra useless conversion, which also gives a small
improvement in performances:

With as simple of a scene as four objects (three operands in a
collection, and the modified one) totalling 20k vertices/faces, this
commit:
* Avoids 2MB memory leak per evaluation (!).
* Speeds up boolean evaluation by 5-10%.

Found while investigating some production files of the Project Heist
here at the Blender Studio.

0 files changed, 0 insertions, 0 deletions