Rollup merge of #142854 - folkertdev:centralize-min-function-alignment, r=workingjubilee

centralize `-Zmin-function-alignment` logic

tracking issue: rust-lang/rust#82232
discussed in: rust-lang/rust#142824 (comment)

Apply the `-Zmin-function-alignment` value to the alignment field of the function attributes when those are created, so that individual backends don't need to consider it.

The one exception right now is cranelift, because it can't yet set the alignment for individual functions, but it can (and does) set the global minimum function alignment.

cc ``@RalfJung`` I think this is an improvement regardless, is there anything else that should be done for miri?

Author: matthiaskrgr