Add fil_system_t::sys_space, fil_system_t::temp_space.
These will replace lookups for TRX_SYS_SPACE or SRV_TMP_SPACE_ID.

mtr_t::m_undo_space, mtr_t::m_sys_space: Remove.

mtr_t::set_sys_modified(): Remove.

fil_space_get_type(), fil_space_get_n_reserved_extents(): Remove.

fsp_header_get_tablespace_size(), fsp_header_inc_size():
Merge to the only caller, innobase_start_or_create_for_mysql().