CLEANUP: admin/halog: improve handling of memory allocation errors
Found via cppcheck --force --enable=all --output-file=haproxy.log :
admin/halog/halog.c:1805:2: warning: If memory allocation fails, then there is a possible null pointer dereference: ustat [nullPointerOutOfMemory]
admin/halog/halog.c:1806:2: warning: If memory allocation fails, then there is a possible null pointer dereference: ustat [nullPointerOutOfMemory]
admin/halog/halog.c:1809:2: warning: If memory allocation fails, then there is a possible null pointer dereference: ustat [nullPointerOutOfMemory]
admin/halog/halog.c:1810:2: warning: If memory allocation fails, then there is a possible null pointer dereference: ustat [nullPointerOutOfMemory]
admin/halog/halog.c:1814:2: warning: If memory allocation fails, then there is a possible null pointer dereference: ustat [nullPointerOutOfMemory]