perl: Fix $h->value_value method when returning an empty value.

Previously this didn't correctly return an empty registry
value.  In this case the length argument to newSVpv would
be 0 which tells Perl to try to calculate the length (we
want newSVpvn instead).

diff --git a/generator/generator.ml b/generator/generator.ml
index 230b66b..96d198d 100755 (executable)
--- a/generator/generator.ml
+++ b/generator/generator.ml
@@ -2439,7 +2439,7 @@ DESTROY (h)
               name;
             pr "      EXTEND (SP, 2);\n";
             pr "      PUSHs (sv_2mortal (newSViv (type)));\n";
-            pr "      PUSHs (sv_2mortal (newSVpv (r, len)));\n";
+            pr "      PUSHs (sv_2mortal (newSVpvn (r, len)));\n";
             pr "      free (r);\n";
 
         | RInt64 ->