fix buggy reference count on refs to SVs with autoviv magic

(resulted in C<my @a; $a[1] = 1; print \$_ for @a> and Data::Dumper
accessing free()d memory)

p4raw-id: //depot/perl@3270

1 files changed, 2 insertions, 0 deletions

diff --git a/pp.c b/pp.c
index 8c48574493..e6a2e1195e 100644
--- a/pp.c
+++ b/pp.c
@@ -512,6 +512,8 @@ refto(SV *sv)
 	    vivify_defelem(sv);
 	if (!(sv = LvTARG(sv)))
 	    sv = &PL_sv_undef;
+	else
+	    SvREFCNT_inc(sv);
     }
     else if (SvPADTMP(sv))
 	sv = newSVsv(sv);