Refactor the isc_log API so it cannot fail on memory failures
The isc_mem API now crashes on memory allocation failure, and this is the next commit in series to cleanup the code that could fail before, but cannot fail now, e.g. isc_result_t return type has been changed to void for the isc_log API functions that could only return ISC_R_SUCCESS.
(cherry picked from commit 0b793166)