Fix Ruby 2.7 options warning during compilation

[64kramsystem]

During compilation, the usual Ruby 2.7 warning is raised:

lib/compiler/utils.rb:93: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
/path/to/ruby/2.7.0/fileutils.rb:463: warning: The called method `cp_r' is defined here

The (conventional) fix applied is to unpack the keyword arguments hash.