add apache 2.4 compatibility

Instead of specifying the args to ap_log_* ourselves, use the APLOG_MARK
helper macro. Since the ap_log_* API changed between httpd 2.2 and 2.4,
this APLOG_MARK macro provides compatibility for both versions' APIs.

In httpd 2.4, unixd_config has been renamed to ap_unixd_config.
cast sizeof() to int for format specifier

sizeof() returns size_t, whereas the format string expects %d (an int).
Cast the result of sizeof() to an int to satisfy the format string.

It's possible that this was done to fix a compiler warning.

Another way to handle this would be to use the %zu format specifier
instead of %d.
config: make cmd_parms->info long when parsing authorizer types