mesa: free idalloc storage for display lists
Fixes a leak:
==46154== 48 bytes in 1 blocks are definitely lost in loss record 1,571 of 1,905
==46154== at 0x48466AF: realloc (vg_replace_malloc.c:1437)
==46154== by 0x5FC98EC: util_idalloc_resize (u_idalloc.c:43)
==46154== by 0x5FC9C16: util_idalloc_alloc_range (u_idalloc.c:125)
==46154== by 0x56FDB9F: _mesa_EndList (dlist.c:13681)
Fixes: b703d7c15f4 ("dlist: store all dlist in a continuous memory block")
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>