Returns the make command for the current platform. For versions of Ruby built on MS Windows with VC++ or
Borland it will return ‘nmake’. On all other platforms, including
Cygwin, it will return ‘make’.
# File lib/rubygems/test_case.rb, line 1170
def self.make_command
ENV["make"] || ENV["MAKE"] || (vc_windows? ? 'nmake' : 'make')
end