According to ISO/IEC 9899:2011, section 7.22.4.4 (The exit function),
"the constant EXIT_FAILURE is the implementation independent way to
issue failures to exit(3)." Whereas EXIT_SUCCESS is the standard way
to return success. Favor this platform independent constants than the
literal numbers.
Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>