Use the newly introduced mem_alloc2() to use the memory that has been
allocated in addition to the requested memory. This is done in order to
avoid wasting memory.

Do not calculate the sizes and offsets of the chunks in advance in
table_cache_init() because it is unknown how much bytes will actually
be allocated by mem_alloc2(). Rather calculate these on the run: after
each chunk is allocated set its size and the offset of the next chunk.

Similar patch approved by:	Marko