Rollup merge of #144829 - Kivooeo:strip-flag, r=WaffleLapkin

Use full flag name in strip command for Darwin

Darwin always uses `rust-objcopy` which supports long-form flags

Solaris unchanged due to not having support for `--discard-all` and only `-x`

fixes rust-lang/rust#135038

r? ````@WaffleLapkin```` (since bot will ping you anyway, feel free to reroll)

Author: samueltardieu