squelch some more type mismatch warnings

SvREFCNT_dec(x ? y : z) did not typecast the right thing due to
missing parens in macro definition

p4raw-id: //depot/perl@16055

1 files changed, 1 insertions, 1 deletions

diff --git a/sv.h b/sv.h
index 92dec20a73..6f95c46a84 100644
--- a/sv.h
+++ b/sv.h
@@ -174,7 +174,7 @@ perform the upgrade if necessary.  See C<svtype>.
 #  endif
 #endif
 
-#define SvREFCNT_dec(sv)	sv_free((SV*)sv)
+#define SvREFCNT_dec(sv)	sv_free((SV*)(sv))
 
 #define SVTYPEMASK	0xff
 #define SvTYPE(sv)	((sv)->sv_flags & SVTYPEMASK)