point-sprite.shader_test is not technically well formed since, in SM4,
the vertex output signature should be:
// Output signature:
// Name Index Mask Register SysValue Format Used
// -------------------- ----- ------ -------- -------- ------- ------
// sv_position 0 xyzw 0 POS float xyzw
// texcoord 0 xy 1 NONE float xy
and the pixel input signature should be:
// Input signature:
// Name Index Mask Register SysValue Format Used
// -------------------- ----- ------ -------- -------- ------- ------
// texcoord 0 xy 0 NONE float xy
so we are not passing "texcoord" properly to the pixel shader, even on
Windows.
