BUG/MINOR: halog: Add OOM checks for calloc() in filter_count_srv_status() and filter...

BUG/MINOR: halog: Add OOM checks for calloc() in filter_count_srv_status() and filter_count_url()

This patch adds missing out-of-memory (OOM) checks after calls to
calloc() in the functions `filter_count_srv_status()` and `filter_count_url()`.
If memory allocation fails, an error message is printed to stderr
and the process exits with status 1. This improves robustness
and prevents undefined behavior in low-memory situations.

Co-authored-by: Christian Norbert Menges <christian.norbert.menges@sap.com>