[dev.cc] build: do not 'clean -i std' between dist and go_bootstrap
Executing 'clean -i std' removes installed Go programs,
including the toolchain binaries we need for building.
It's not clear why the 'clean -i std' is here in the first place.
cmd/dist just removed the entire pkg tree, so everything is new.
The only reason for 'clean -i std' would be if you don't trust
that dist compiled the packages properly. If that's true for
some reason, we can fix cmd/dist, or add -a to the install
commands that follow. Perhaps clean -i std should not
remove tools, or perhaps std should not expand to any tools.
Not sure.
Also remove banner from make.bat and make.rc that was
already removed from make.bash. cmd/dist prints it now.