extlibs.rb: patch options

* tool/extlibs.rb (do_patch): let "patch" command change the
  working directory and open the patch file there, instead of
  spawn options, so that proper error message will be shown by the
  command not just "chdir" or "open".

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51812 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,10 @@
+Wed Sep  9 13:38:56 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* tool/extlibs.rb (do_patch): let "patch" command change the
+	  working directory and open the patch file there, instead of
+	  spawn options, so that proper error message will be shown by the
+	  command not just "chdir" or "open".
+
 Wed Sep  9 11:33:05 2015  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* common.mk (update-gems): use BASERUBY instead of RUNRUBY.

tool/extlibs.rb

@@ -70,7 +70,7 @@ def do_patch(dest, patch, args)
     $stdout.puts "applying #{patch} under #{dest}"
     $stdout.flush
   end
-  Process.wait(Process.spawn("patch", *args, in: File.join(dest, patch), chdir: dest))
+  Process.wait(Process.spawn("patch", "-d", dest, "-i", patch, *args))
   $?.success? or raise "failed to patch #{patch}"
 end