compilation fixes for sys-devel/gcc-11.2.0:11

for example:

sql/sql_prepare.cc:5714:63: error: 'static void Ed_result_set::operator delete(void*, MEM_ROOT*)' called on pointer returned from a mismatched allocation function [-Werror=mismatched-new-delete]

sql/sql_cursor.h

@@ -39,7 +39,7 @@ class JOIN;
   its base class.
 */
 
-class Server_side_cursor: protected Query_arena, public Sql_alloc
+class Server_side_cursor: protected Query_arena
 {
 protected:
   /** Row destination used for fetch */
@@ -61,6 +61,8 @@ class Server_side_cursor: protected Query_arena, public Sql_alloc
   }
   virtual ~Server_side_cursor();
 
+  static void *operator new(size_t size, MEM_ROOT *mem_root)
+  { return alloc_root(mem_root, size); }
   static void operator delete(void *ptr, size_t size);
   static void operator delete(void *, MEM_ROOT *){}
 };

sql/sql_prepare.h

@@ -115,7 +115,7 @@ class Ed_row;
   automatic type conversion.
 */
 
-class Ed_result_set: public Sql_alloc
+class Ed_result_set
 {
 public:
   operator List<Ed_row>&() { return *m_rows; }
@@ -129,6 +129,8 @@ class Ed_result_set: public Sql_alloc
 
   size_t get_field_count() const { return m_column_count; }
 
+  static void *operator new(size_t size, MEM_ROOT *mem_root)
+  { return alloc_root(mem_root, size); }
   static void operator delete(void *ptr, size_t size) throw ();
   static void operator delete(void *, MEM_ROOT *){}
 private: