Fix executable? and executable_real? file permissions predicates

Author: andrykonchin

lib/mspec/guards/superuser.rb

@@ -6,10 +6,20 @@ def match?
   end
 end
 
+class RealSuperUserGuard < SpecGuard
+  def match?
+    Process.uid == 0
+  end
+end
+
 def as_superuser(&block)
   SuperUserGuard.new.run_if(:as_superuser, &block)
 end
 
+def as_real_superuser(&block)
+  RealSuperUserGuard.new.run_if(:as_real_superuser, &block)
+end
+
 def as_user(&block)
   SuperUserGuard.new.run_unless(:as_user, &block)
 end