Cache the result of DNA_elem_array_size which was being called
for each element when reconstructing each struct.
Also skip padding members during reconstruction.
Gives ~18% overall speedup loading 10_010_A.anim.blend (r3154)
from the spring project.# Please enter the commit message for your changes. Lines starting
Note, this was reverted recently because it caused T62181
Changes to DNA_sdna_patch_struct_member_nr were needed which
caused issues loading old 2.8x files.
e5ab2b9c62