dump: Fix one-page mapping dump

The iov array for 1-page mapping would be zero. Fix this silly mistake.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

parasite-syscall.c

@@ -493,7 +493,7 @@ static unsigned int vmas_pagemap_size(struct vm_area_list *vmas)
 	 */
 
 	return sizeof(struct parasite_dump_pages_args) +
-		vmas->priv_size * sizeof(struct iovec) / 2;
+		(vmas->priv_size + 1) * sizeof(struct iovec) / 2;
 }
 
 #define PME_PRESENT	(1ULL << 63)

shmem.c

@@ -334,11 +334,11 @@ static int dump_one_shmem(struct shmem_info_dump *si)
 	if (err)
 		goto err_unmap;
 
-	iovs = xmalloc((nrpages / 2) * sizeof(struct iovec));
+	iovs = xmalloc(((nrpages + 1) / 2) * sizeof(struct iovec));
 	if (!iovs)
 		goto err_unmap;
 
-	pp = create_page_pipe(nrpages / 2, iovs);
+	pp = create_page_pipe((nrpages + 1) / 2, iovs);
 	if (!pp)
 		goto err_iovs;