security/bsmtrace3: update to the 3.1 -fno-common build fix
The only changes between 3.0 and 3.1 are a change to the README to note work
sponsored by an organization, and the -fno-common build fix.
-fno-common is now the default in LLVM 11/GCC 10.
PR: 248756
Approved by: csjp (maintainer, also discussed with)
MFH: 2020Q3 (-fno-common build fix)