Update API to use (char *) for email addresses and hostnames.

Reduces number of silly casts in OpenSSL code and likely most
applications.  Consistent with (char *) for "peername" value from
X509_check_host() and X509_VERIFY_PARAM_get0_peername().

(Imported from upstream's e83c913723fac7432a7706812f12394aaa00e8ce.)

Change-Id: Id0fc11773a0cee8933978cd4bdbd8251fd7cfb5f
7 files changed