Refactor Process.clock_gettime spec to give more information when it fails

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66635 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/core/process/clock_gettime_spec.rb

@@ -5,9 +5,10 @@ describe "Process.clock_gettime" do
   # RHEL: https://rubyci.org/logs/rubyci.s3.amazonaws.com/rhel_zlinux/ruby-trunk/log/20181229T063303Z.fail.html.gz
   # Solaris: https://rubyci.org/logs/rubyci.s3.amazonaws.com/unstable11x/ruby-trunk/log/20181229T002409Z.fail.html.gz
   platform_is_not :windows, :linux, :solaris do
-    it 'can be called with all declared clocks' do
-      Process.constants.select { |c| c.to_s.start_with?('CLOCK_') }.each do |c|
-        Process.clock_gettime(Process.const_get(c)).should be_an_instance_of(Float)
+    Process.constants.select { |c| c.to_s.start_with?('CLOCK_') }.each do |c|
+      it "can be called with Process::#{c}" do
+        value = Process.const_get(c)
+        Process.clock_gettime(value).should be_an_instance_of(Float)
       end
     end
   end