rw_lock_t: Do not make writer_is_wait_ex a bit-field.  There are no fields
yet that could be fused to the same machine word, but we play it safe,
because the field writer_is_wait_ex may be modified by several threads
simultaneously.  Such fields should always be allocated an own machine
word.

dict_table_t: Change the type of all bit-fields to "unsigned".  Make
"space" a bit-field of 32 bits.  Move name_hash and id_hash after all
bit-fields, so that the bit-fields can be allocated together.  Do not
make autoinc_inited a bit-field, as we cannot allocate any field
from the same machine word.

dict_build_table_def_step(): Pass a local variable to
fil_create_new_single_table_tablespace() and initialize table->space
from it after the call, now that table->space is a bit-field.