Rollup merge of #134211 - flba-eb:add_qnx_archiver, r=compiler-errors

On Neutrino QNX, reduce the need to set archiver via environment variables

This adds support for automatically selecting the correct `ar` tool when compiling for Neutrino QNX.
Once rust-lang/cc-rs#1319 is merged and a new cc version is integrated, all environment variables of the [Neutrino documentation](https://github.com/rust-lang/rust/blob/stable/src/doc/rustc/src/platform-support/nto-qnx.md) can be removed.

CC: ````````@jonathanpallant```````` ````````@japaric```````` ````````@gh-tr```````` ````````@AkhilTThomas````````