avoid sign mismatch warning in openssl_hostname_validation.c sample/openssl_hostname_validation.c: In function 'matches_common_name': sample/openssl_hostname_validation.c:80: warning: comparison between signed and unsigned integer expressions sample/openssl_hostname_validation.c: In function 'matches_subject_alternative_name': sample/openssl_hostname_validation.c:124: warning: comparison between signed and unsigned integer expressions