Remove RUBY_PLATFORM conditional from gemspec
Remove RUBY_PLATFORM conditional from gemspec

This conditional is of no use. The gem specification generated is not
dynamic and will always contain these gems. In order to support JRuby
properly we'll need to create a separate gemspec.

hilben/webmock,influxdb/webmock,hobodave/webmock,qrush/webmock,maruware/webmock,davidbegin/webmock,xuwupeng2000/webmock,henrik/webmock,ixti/webmock,VincentZhao/webmock,avantcredit/webmock,sinisterstuf/webmock,spjsschl/webmock,arronmabrey/webmock,Omnihuron/webmock,bblimke/webmock,webmock/webmock,taiki45/webmock,sferik/webmock