strerror_s is the windows alternative of strerror_r used by EFL.
strerror_s never return the error code with the message as
strerror_r does, because of that, while comparing the first 14
characters of Unknown error to the message from unknown code 4096
(Unknown error) they were accusing being different - in UNIX this
works because the message returned is Unknown error 4096.
This error was noticeable at eina_error_test_failures test case.
This Diff adds the error code to the message in case of an `Unknown
error`, making the windows implementation compliant with UNIX.