Do not try to chown/chgrp when installing unless running
as root. This is done for the same reasons as the patch for 
lib/rubygems/ext/ext_conf_builder.rb in the Ruby port.

Don't have it accidently use gmake, because the makefiles
created can use BSD make extensions.

Index: lib/rake/extensiontask.rb
--- lib/rake/extensiontask.rb.orig
+++ lib/rake/extensiontask.rb
@@ -169,6 +169,7 @@ module Rake
           make_command_line << "install"
           make_command_line << "sitearchdir=#{relative_lib_path}"
           make_command_line << "sitelibdir=#{relative_lib_path}"
+          make_command_line << "INSTALL_PROG=/usr/bin/install -c -m 0755" unless Process.uid == 0
           make_command_line << "target_prefix="
 
           sh(*make_command_line, chdir: tmp_path)
@@ -494,20 +495,7 @@ Java extension should be preferred.
     end
 
     def make
-      unless @make
-        @make =
-          if RUBY_PLATFORM =~ /mswin/ then
-            'nmake'
-          else
-            ENV['MAKE'] || find_make
-          end
-      end
-
-      unless @make
-        raise "Couldn't find a suitable `make` tool. Use `MAKE` env to set an alternative."
-      end
-
-      @make
+      @make ||= ENV['MAKE'] || 'make'
     end
 
     def find_make