Do not convert BC1 LUT to UINT32

[radarhere]

Pillow/src/libImaging/BcnDecode.c

Lines 43 to 49 in b8abded

	#define LOAD32(p) (p)[0] | ((p)[1] << 8) | ((p)[2] << 16) | ((p)[3] << 24)
	static void
	bc1_color_load(bc1_color *dst, const UINT8 *src) {
	dst->c0 = LOAD16(src);
	dst->c1 = LOAD16(src + 2);
	dst->lut = LOAD32(src + 4);

Pillow/src/libImaging/BcnDecode.c

Lines 106 to 109 in b8abded

	for (n = 0; n < 16; n++) {
	cw = 3 & (col.lut >> (2 * n));
	dst[n] = p[cw];
	}

With a little maths and changing the loop of size 16 to two range loops of size 4 each, this code can be changed to avoid the UINT32. If you think that changing the size of the loop is misleading to the reality of the image, it's not - looking at https://learn.microsoft.com/en-us/windows/win32/direct3d10/d3d10-graphics-programming-guide-resources-block-compression#bc1, you can see that the LUT is actually representing a 4x4 block.