playground/c: update bld methods. Use write_config_header for variants so cleanall doesn't delete them.
playground/c: update bld methods. Use write_config_header for variants so
cleanall doesn't delete them.

hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR,hlange/LogSoCR