Rollup merge of #50251 - alexcrichton:wasm-no-threads, r=eddyb
Rollup merge of #50251 - alexcrichton:wasm-no-threads, r=eddyb

rustc: Disable threads in LLD for wasm

Upstream bug reports (rustwasm/wasm-bindgen#119) show that this may be the
culprit of odd crashes/hangs. The linker is a tiny fraction of build time anyway
right now so let's disable it and figure out how to possibly reenable it later
if necessary.

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