Do not mark large objects for evacuation

We previously copied entire page-aligned regions containing a single
large object under certain unlikely conditions. Aside from occasionally
causing us to run out of memory in the GC under even less likely
conditions, this generally appears to be wasted effort. The copy
is allocated before deallocating from-space regions, so there is
no reason to believe it will reduce fragmentation at the region
level, which seems to be its only plausible benefit.

Remove the code to copy such objects, since that situation no
longer arises.

Have the space flip clear live_bytes, fixing an earlier bug that
otherwise causes this CL to break. (Thanks to lokeshgidra@ for this
piece.)

Add a large comment to live_bytes_ better explaining its use.

Drive-by-fix: Remove "temporary" output for b/116087961 that has
been closed for 2 years.

Test: Build and boot AOSP. Run test from bug repeatedly.
Bug: 191912426
Change-Id: I1603cd898aedcbcdd75fe019770213f0eae506d3
3 files changed