oar-properties: fix gpu_idx computation

Quickfix to be able to generate oar properties until I provide a proper patch for https://intranet.grid5000.fr/bugzilla/show_bug.cgi?id=15068.

It doesn't fix the fact that GPUs are not using all processors, but it does fix how the processor is split when the number of cores cannot be divided evenly. In the case of abacus9 there are 4 GPUs sharing a 10 cores processor, so 2 of them will have 3 cores while the other 2 will have 2.

lib/refrepo/gen/oar-properties.rb

@@ -1329,7 +1329,10 @@ def extract_clusters_description(clusters, site_name, options, data_hierarchy, s
                   raise "Could not find a GPU on CPU #{cpu_num} for core #{row[:cpuset]}"
                 end
               else
-                gpu_idx = core_num / (cpu_core_count / numa_gpus.length)
+                # The parenthesis order is important: we want to keep the
+                # integer division to generate an integer index, so we want to
+                # do the multiplication first.
+                gpu_idx = (core_num * numa_gpus.length) / cpu_core_count
                 selected_gpu = numa_gpus[gpu_idx]
               end
               # id of the selected GPU in the node