[GR-32856] Only expect Kernel#loop to be in the profile

* If Kernel#loop compiles (OSR) or some other call inside compiles,
  they will inline everything from there, and there will not be guest
  safepoints inside for the block (2 levels).

Author: eregon

spec/truffle/tools_spec.rb

@@ -70,7 +70,7 @@ def foo
       RUBY
       out = ruby_exe(code, options: "--cpusampler")
       out.should.include?(":kill")
-      out.should.include?("block (2 levels) in Object#foo")
+      out.should.include?("Kernel#loop")
       out.should_not.include?('KillException')
       $?.should.success?
     end