Rollup merge of #29876 - cardoe:i586-build-fix, r=alexcrichton
Rollup merge of #29876 - cardoe:i586-build-fix, r=alexcrichton

On distros that use i486 or i586 in their CHOST, Rust will fail to build
because it is not handling i486 or i586 like i686 is handled. This
changes the match to do work for all instances of i?86 instead of just
i686. The Yocto Project still uses i586 as a target.

Signed-off-by: Doug Goldstein <8172f793ca553050868d487fd13b508d19cae503@cardoe.com>

GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust