Remove redundant access() calls for File.identical?

* The stat() calls done before already prove the files exist.
* Also those calls returned an Integer, so the result was always true.
* File.identical? returns true even if the files don't have read permission.
* Remove now-unused access(), one might think it's faster for File.exist?
  but actually on Linux the truffleposix_stat_mode() approach seems faster (1.4Mi/s vs 1.0Mi/s).

Author: eregon

src/main/ruby/truffleruby/core/file.rb

@@ -732,8 +732,7 @@ def self.identical?(orig, copy)
 
     return false if Primitive.nil?(st_o) || Primitive.nil?(st_c)
 
-    st_o.dev == st_c.dev and st_o.ino == st_c.ino and st_o.ftype == st_c.ftype and
-      POSIX.access(orig, Constants::R_OK) && Primitive.as_boolean(POSIX.access(copy, Constants::R_OK))
+    st_o.dev == st_c.dev and st_o.ino == st_c.ino and st_o.ftype == st_c.ftype
   end
 
   ##

src/main/ruby/truffleruby/core/posix.rb

@@ -171,7 +171,6 @@ def self.attach_function_eagerly(native_name, argument_types, return_type,
   end
 
   # Filesystem-related
-  attach_function :access, [:string, :int], :int
   attach_function :chdir, [:string], :int
   attach_function :chmod, [:string, :mode_t], :int
   attach_function :chown, [:string, :uid_t, :gid_t], :int