Revert "Revert "Skip BUGs on Solaris""

This reverts commit 84dca8eff0.

"exceution expired" occurred on Solaris.
https://rubyci.org/logs/rubyci.s3.amazonaws.com/solaris11s-sunc/ruby-master/log/20190901T072504Z.fail.html.gz

test/drb/drbtest.rb

@@ -115,7 +115,7 @@ module DRbBase
         end
       }
     end
-    @drb_service.finish
+    @drb_service&.finish
   end
 end
 

test/drb/test_drbssl.rb

@@ -41,6 +41,7 @@ end
 class TestDRbSSLCore < Test::Unit::TestCase
   include DRbCore
   def setup
+    skip 'FIXME: BUG in OpenSSL on Solaris' if RUBY_PLATFORM =~ /solaris/i
     @drb_service = DRbSSLService.new
     super
     setup_service 'ut_drb_drbssl.rb'
@@ -59,6 +60,7 @@ end
 class TestDRbSSLAry < Test::Unit::TestCase
   include DRbAry
   def setup
+    skip 'FIXME: BUG in OpenSSL on Solaris' if RUBY_PLATFORM =~ /solaris/i
     @drb_service = DRbSSLService.new
     super
     setup_service 'ut_array_drbssl.rb'