libagx: assert alignment for copies

would have exposed the bug fixed.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34326>

src/asahi/libagx/copy.cl

@@ -7,12 +7,17 @@
 KERNEL(32)
 libagx_fill(global uint32_t *address, uint32_t value)
 {
+   assert((((uintptr_t)address) & 0x3) == 0);
+
    address[cl_global_id.x] = value;
 }
 
 KERNEL(32)
 libagx_copy_uint4(global uint4 *dest, global uint4 *src)
 {
+   assert((((uintptr_t)dest) & 0xf) == 0);
+   assert((((uintptr_t)src) & 0xf) == 0);
+
    dest[cl_global_id.x] = src[cl_global_id.x];
 }