add hostname helper

fixes platforms that are missing the hostname executable by
providing for an array of fallback commands that return
equivalent information

mspec/lib/mspec/helpers/environment.rb

@@ -37,4 +37,13 @@ def dev_null
       "/dev/null"
     end
   end
+
+  def hostname
+    commands = ['hostname', 'uname -n']
+    commands.each do |command|
+      name = `#{command}`
+      return name.strip if $?.success?
+    end
+    raise Exception, "hostname: unable to find a working command"
+  end
 end

spec/ruby/library/socket/socket/gethostname_spec.rb

@@ -2,9 +2,9 @@
 require File.expand_path('../../fixtures/classes', __FILE__)
 
 describe "Socket.gethostname" do
-  # This currently works in Unix and Windows. Feel free to add guards
-  # for other platforms.
+  # This currently works in Unix and Windows. Edit the helper
+  # to add other platforms.
   it "returns the host name" do
-    Socket.gethostname.should == `hostname`.strip
+    Socket.gethostname.should == hostname
   end
 end