Add the LBO paper.

Author: ltratt

softdev.bib

@@ -2680,3 +2680,11 @@ @inproceedings{coblenz21bronze
     year = 2022,
     month = May
 }
+
+@misc{cai21lbo,
+    title = "An Empirical Lower Bound on the Overheads of Production Garbage Collectors",
+    author = "Zixian Cai and Stephen M. Blackburn and Michael D. Bond and Martin Maas",
+    year = 2021,
+    month = Dec,
+    url = "https://arxiv.org/abs/2112.07880"
+}