bluespec-compiler fails to build on Linux host

[tmarkettos]

bluespec-compiler fails to build on Ubuntu 21.10 because bsc have renamed their Makefile to GNUmakefile. cheribuild expects those to have a 'distclean' rule, which bsc doesn't have:

cheribuild$ ./cheribuild.py bluespec-compiler
Checking /home/atm26/.config/cheribuild.json since /local/scratch/atm26/CTSRD-CHERI/cheribuild/cheribuild.json doesn't exist
Note: Configuration file /home/atm26/.config/cheribuild.json does not exist, using only command line arguments.
Sources will be stored in /home/atm26/cheri
Build artifacts will be stored in /home/atm26/cheri/output
cd /local/scratch/atm26/CTSRD-CHERI/cheribuild && git fetch
cd /home/atm26/cheri/bsc && git fetch
Skipping update: Current HEAD is up-to-date or ahead of upstream.
cd /home/atm26/cheri/bsc && gmake distclean
gmake: *** No rule to make target 'distclean'. Stop.
Warning: 'gmake distclean' FD flags for <stdin> changed from 0x80002 to 0x80402 - resetting them.
Fatal error (in target bluespec-compiler): Command `gmake distclean` failed with non-zero exit code 2. Working directory was /home/atm26/cheri/bsc