mathlib3

d9370e03 - fead(data/support): add `support_smul` (#6569)

fead(data/support): add `support_smul` (#6569) * add `smul_ne_zero`; * rename `support_smul_subset` to `support_smul_subset_right`; * add `support_smul_subset_left` and `support_smul`.