mysql-test/suite/heap/heap.result:
  Added test case for MDEV-436
mysql-test/suite/heap/heap.test:
  Added test case for MDEV-436
storage/heap/hp_block.c:
  Don't allocate a set of HP_PTRS when not needed. This saves us about 1024 bytes for most allocations.
storage/heap/hp_create.c:
  Made the initial allocation of block sizes depending on min_records and max_records.