Add debug option to check ci failures on solaris

failed to start extserv?:
- 20181020T132506Z.fail.html.gz

BUG in sysread of OpenSSL:
- 20181020T132408Z.fail.html.gz
- 20181020T131807Z.fail.html.gz

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65304 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/drb/drbtest.rb

@@ -11,6 +11,9 @@ class DRbService
   @@ruby << "-d" if $DEBUG
   def self.add_service_command(nm)
     dir = File.dirname(File.expand_path(__FILE__))
+    if /ssl/ =~ nm && RUBY_PLATFORM =~ /solaris/i
+      @@ruby[1..-1] = "-dv"
+    end
     DRb::ExtServManager.command[nm] = @@ruby + ["#{dir}/#{nm}"]
   end