Bump ABC

[povik]

What are the reasons/motivation for this change?

ABC has new features (timing for &nf blackboxes; improved LUT mapping); also I will push for our fork to converge with upstream -- for that let's pull changes from upstream to our fork first.

[povik]

6.2.2. Re-integrating ABC results.
../tools/autotest.sh: line 171: 48993 Segmentation fault: 11  "$toolsdir"/../../yosys -b "verilog $backend_opts" -o ${bn}_syn${test_count}.v "$@"

Huh, does ABC now write out BLIFs which make Yosys crash?

[povik]

The failures were due to &nf losing PI/PO names. Upstream fix is at berkeley-abc/abc#317

[povik]

This should be good to go. The content is:

• YosysHQ/abc@bf64a92
• Handle edge case in Gia_ManTransferTiming berkeley-abc/abc#317
• Fix types in call to atomic_store_explicit berkeley-abc/abc#318