main: increase thread stack size for non-x86_64 backends
I observed a stack overflow during x86_64 CodeGen in a debug compiler
compiled by the llvm backend. This happens while compiling
`main.buildOutputType` due to the Air being nested almost 500 levels.
f98f5a5f74Jacob Young committed on 2/15/2025, 8:45:21 AMparent4ea18c2