allow use of unzip version 6.0

Unzip 6.0 changes the name of the fourth column in the "unzip -lv"
output from "Ratio" to "Cmpr".  Allow either name so that
dump-package-stats works with both unzip 5 and unzip 6.
diff --git a/tools/dump-package-stats b/tools/dump-package-stats
index 589bab5..d11e727 100755
--- a/tools/dump-package-stats
+++ b/tools/dump-package-stats
@@ -102,7 +102,7 @@
                 $1 != "Length" ||
                 $2 != "Method" ||
                 $3 != "Size" ||
-                $4 != "Ratio" ||
+                ($4 != "Ratio" && $4 != "Cmpr") ||
                 $5 != "Date" ||
                 $6 != "Time" ||
                 $7 != "CRC-32" ||