libventi: add VtEntryNoArchive from liboventi, for use with fossil

R=rsc
CC=plan9port.codebot
http://codereview.appspot.com/5298088
diff --git a/include/venti.h b/include/venti.h
index 632746d..d6b753b 100644
--- a/include/venti.h
+++ b/include/venti.h
@@ -139,6 +139,7 @@
 	_VtEntryDepthMask = 7<<2,	/* mask for pointer depth */
 	VtEntryLocal = 1<<5,		/* for local storage only */
 	_VtEntryBig = 1<<6,
+	VtEntryNoArchive = 1<<7,	/* for local storage only */
 };
 enum
 {