UI: use correct singular and plural nouns in report messages

Differential Revision: https://developer.blender.org/D5729

source/blender/blenkernel/intern/packedFile.c

@@ -267,7 +267,11 @@ void BKE_packedfile_pack_all(Main *bmain, ReportList *reports, bool verbose)
   }
 
   if (tot > 0) {
-    BKE_reportf(reports, RPT_INFO, "Packed %d files", tot);
+    BKE_reportf(reports,
+                RPT_INFO,
+                tot == 1 ? "Packed %d file" :
+                           "Packed %d files",
+                tot);
   }
   else if (verbose) {
     BKE_report(reports, RPT_INFO, "No new files have been packed");