Fix x509_check_host return value

[evanrittenhouse]

The x509_check_host docs state:

X509_check_host checks if x509 matches the DNS name chk. It returns one on match, zero on mismatch, or a negative number on error.

The current implementation will return true for 1, -1, and -2, therefore returning an incorrect value if any of the above error cases are hit.