initialize local variable addr in ippool_new()

Coverity points out that addr.len was potentially being used
uninitialized, via calls to in46a_inc(&addr).

Change-Id: Idb67394e5f4c2072380a33f46c848d92c4317245
Related: CID#174189
diff --git a/lib/ippool.c b/lib/ippool.c
index 36121ee..6f3d06e 100644
--- a/lib/ippool.c
+++ b/lib/ippool.c
@@ -202,7 +202,7 @@
 	/* Parse only first instance of pool for now */
 
 	int i;
-	struct in46_addr addr;
+	struct in46_addr addr = { 0 };
 	size_t addrprefixlen;
 	struct in46_addr stataddr;
 	size_t stataddrprefixlen;