Bug #19852 Restoring backup made from cluster with full data memory fails

- post merge fixes for 5.1

storage/ndb/src/kernel/blocks/dbtup/DbtupMeta.cpp

@@ -535,9 +535,11 @@ void Dbtup::execTUP_ADD_ATTRREQ(Signal* signal)
 #endif
   
   {
-    ndbrequire(regTabPtr.p->m_offsets[MM].m_fix_header_size > 0);
-    Uint32 noRowsPerPage =
-      ZWORDS_ON_PAGE/regTabPtr.p->m_offsets[MM].m_fix_header_size;
+    Uint32 fix_tupheader = regTabPtr.p->m_offsets[MM].m_fix_header_size;
+    if(regTabPtr.p->m_attributes[MM].m_no_of_varsize != 0)
+      fix_tupheader += Tuple_header::HeaderSize + 1;
+    ndbassert(fix_tupheader > 0);
+    Uint32 noRowsPerPage = ZWORDS_ON_PAGE / fix_tupheader;
     Uint32 noAllocatedPages =
       (fragOperPtr.p->minRows + noRowsPerPage - 1 )/ noRowsPerPage;
     if (fragOperPtr.p->minRows == 0)