[cleanup] Convert XMALLOC/memset to XCALLOC

Simple conversion of XMALLOC/memset to XCALLOC
diff --git a/lib/sockunion.c b/lib/sockunion.c
index 3750295..75419b1 100644
--- a/lib/sockunion.c
+++ b/lib/sockunion.c
@@ -180,8 +180,7 @@
   int ret;
   union sockunion *su;
 
-  su = XMALLOC (MTYPE_SOCKUNION, sizeof (union sockunion));
-  memset (su, 0, sizeof (union sockunion));
+  su = XCALLOC (MTYPE_SOCKUNION, sizeof (union sockunion));
 
   ret = inet_pton (AF_INET, str, &su->sin.sin_addr);
   if (ret > 0)			/* Valid IPv4 address format. */