THRIFT-979. rb: ruby bindings used to work on jruby

Make a dummy makefile so that JRuby doesn't complain.

Patch: Jeff Hodges

git-svn-id: https://svn.apache.org/repos/asf/thrift/trunk@1036267 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/rb/ext/extconf.rb b/lib/rb/ext/extconf.rb
index 07558b8..36dac9b 100644
--- a/lib/rb/ext/extconf.rb
+++ b/lib/rb/ext/extconf.rb
@@ -17,10 +17,14 @@
 # under the License.
 # 
 
-require 'mkmf'
+if defined?(RUBY_ENGINE) && RUBY_ENGINE =~ /jruby/
+  File.open('Makefile', 'w'){|f| f.puts "all:\n\ninstall:\n" }
+else
+  require 'mkmf'
 
-$CFLAGS = "-g -O2 -Wall -Werror"
+  $CFLAGS = "-g -O2 -Wall -Werror"
 
-have_func("strlcpy", "string.h")
+  have_func("strlcpy", "string.h")
 
-create_makefile 'thrift_native'
+  create_makefile 'thrift_native'
+end