selftests/bpf: Make %.test.d prerequisite order only

%.test.o should depend on %.test.d order-only to avoid unnecessary
recompilations due to compiler dumping .d and .o files in random
order.

Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/all/gSoCpn9qV5K0hRvrvYlrw2StRntsvZcrUuDfkZUh1Ang9E6yZ9XJGYDuIP9iCuM2YTVhSEzEXCteQ94_0uIUjx_mXwupFJt64NJaiMr99a0=@pm.me
Link: https://lore.kernel.org/all/FnnOUuDMmf0SebqA1bb0fQIW4vguOZ-VcAlPnPMnmT2lJYxMMxFAhcgh77px8MsPS5Fr01I0YQxLJClEJTFWHdpaTBVSQhlmsVTcEsNQbV4=@pm.me
Link: https://lore.kernel.org/bpf/yyjJRl5LODbI4-FseU0wIP5e4ik0zAy7Sy-5eGwrzG_UanI8rwWlQPfXAFnn_27hoZFogoUHRSWxFsLk7hPr0b6P5TZ3cRrM30_ggnu555M=@pm.me