HPCC-18106 Coverity: Incorrect expression (MISSING_COMMA)

Slight reduction in effectiveness of jptree common-value cache...

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>

system/jlib/jptree-attrvalues.hpp

@@ -5,7 +5,7 @@
     "*",
     "\\,",
     "0 secs",
-    "-1"
+    "-1",
     "1:1",
     "1:M",
     "Access to cluster topology",