RFR: Verifier should print verification label at liveness verification

[Aleksey Shipilev]

Trivial: print out the label.

$ hg diff
diff -r 80dac6eb4247 src/share/vm/gc/shenandoah/shenandoahVerifier.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahVerifier.cpp	Wed Oct 04 14:12:29 2017 +0200
+++ b/src/share/vm/gc/shenandoah/shenandoahVerifier.cpp	Thu Oct 05 09:28:24 2017 +0200
@@ -801,8 +801,8 @@
         ResourceMark rm;
         stringStream ss;
         r->print_on(&ss);
-        fatal("Live data should match: region-live = " SIZE_FORMAT ", verifier-live = "
UINT32_FORMAT "\n%s",
-              reg_live, verf_live, ss.as_string());
+        fatal("%s: Live data should match: region-live = " SIZE_FORMAT ", verifier-live = "
UINT32_FORMAT "\n%s",
+              label, reg_live, verf_live, ss.as_string());
       }
     }
   }

Testing: injecting failures and examining hs_err

Thanks,
-Aleksey