Fix memory leaks in mro_package_moved

This commit adds a new HV_FETCH_EMPTY_HE flag for hv_common. It is to
be used in conjunction with HV_FETCH_LVALUE. It just stops the newly-
created HE from having a new undef scalar assigned to it.

This allows code to call hv_common just once instead of an hv_exists/
hv_store pair.

It was such a double hv_common call that I was trying to avoid with
HV_FETCH_LVALUE, without realising that it was leaking.

1 files changed, 1 insertions, 0 deletions

diff --git a/hv.h b/hv.h
index 81a4d89beb..33ecef5d0f 100644
--- a/hv.h
+++ b/hv.h
@@ -590,6 +590,7 @@ a string/length pair, and no precomputed hash.
 #define HV_FETCH_LVALUE		0x10
 #define HV_FETCH_JUST_SV	0x20
 #define HV_DELETE		0x40
+#define HV_FETCH_EMPTY_HE	0x80 /* Leave HeVAL null. */
 
 /*
 =for apidoc newHV