Set Oboe::API to no-op when c-ext not loaded
Set Oboe::API to no-op when c-ext not loaded

tlunter/oboe-ruby,appneta/ruby-traceview,appneta/ruby-traceview,tlunter/oboe-ruby,boyang-li/oboe-ruby,boyang-li/oboe-ruby,appneta/ruby-traceview,appneta/ruby-traceview,tlunter/oboe-ruby,boyang-li/oboe-ruby,tlunter/oboe-ruby,boyang-li/oboe-ruby