changed log behavior again to ugly macro. problem with solution before
was that the global variable for the log facility is not shared between
different pam modules... so far this is the only solution i have figured
out that satisfies the following:

1) have one location where message template is defined
2) always have a standard opaque log facility
3) do not specify the log facility as an argument during every log attempt

the drawback is that
1) there is an ugly macro... (i hope its really doing what intended)
2) for other pam modules that want to use the logging macros the var
name of the data transfer object MUST be x509_info. fortunately the
compiler throws an error if not...