scripts: Renamed -c/--compare -> -C/--compare

The lowercase -c/--compare felt clunky. I think because we tend towards
using uppercase for flags that operate on csv rows, such as -D/--define,
-L/--add-label (plot.py), etc.

scripts/stack.py

@@ -1188,7 +1188,7 @@ if __name__ == "__main__":
             action='store_true',
             help="Only show percentage change, not a full diff.")
     parser.add_argument(
-            '-c', '--compare',
+            '-C', '--compare',
             type=lambda x: tuple(v.strip() for v in x.split(',')),
             help="Compare results to the row matching this by pattern.")
     parser.add_argument(