Use SvREFCNT_dec_NN in one place in hv.h

In this instance, we know that av is not null, so no need to check
whether it is

1 files changed, 1 insertions, 1 deletions

diff --git a/hv.c b/hv.c
index e9e3b276e8..966a12f58e 100644
--- a/hv.c
+++ b/hv.c
@@ -2213,7 +2213,7 @@ Perl_hv_kill_backrefs(pTHX_ HV *hv) {
 	HvAUX(hv)->xhv_backreferences = 0;
 	Perl_sv_kill_backrefs(aTHX_ MUTABLE_SV(hv), av);
 	if (SvTYPE(av) == SVt_PVAV)
-	    SvREFCNT_dec(av);
+	    SvREFCNT_dec_NN(av);
     }
 }