Rewrite the 'rectangularness' computation. Since 'rectangularness' is now the largest-scale subdivision, it should not (anymore) have anything to do with the kernel layout. Rectangularness is now nothing but the shape 'aspect ratio', (rows/columns), of the destination matrix. This keeps concepts simpler and more orthogonal -- rectangularness is a property of the destination matrix alone, orthogonal to kernel. This will allow writing better, simpler block_map logic.
Rewrite the 'rectangularness' computation. Since 'rectangularness' is now the largest-scale subdivision, it should not (anymore) have anything to do with the kernel layout. Rectangularness is now nothing but the shape 'aspect ratio', (rows/columns), of the destination matrix. This keeps concepts simpler and more orthogonal -- rectangularness is a property of the destination matrix alone, orthogonal to kernel. This will allow writing better, simpler block_map logic.

PiperOrigin-RevId: 270108416

google/ruy,google/ruy,google/ruy,google/ruy