make targets
make targets

This produces a list of currently supported targets.  Here "supported"
means "built in make universe" on the theory that those targets are
more supported than any that might work in 'make buildworld TARGET=x
TARGET_ARCH=y' since the latter are less tested.

Suggested by: rwatson

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase