[llvm] [CI] Disable precompiled headers in monolithic-*.sh (PR #143369)

[Kajetan Puchalski via llvm-commits]

mrkajetanp wrote:

> I'm not sure premerge is the place for that. We want to be testing as standard of a configuration as possible, and since PCH is enabled by default for Flang, premerge should probably stick with that (barring other issues).

I don't have very strong opinions here to be honest, so I'm happy with this going wherever you think it should go. Either way it's a slight tradeoff. I'd go the way of putting it in pre-merge just on account of it being a pretty easy mistake for people to make. The intention with introducing pch was for people to still write code as if they weren't there but use pch to speed up the compilation times. Putting it in post-merge bots might cause some commit inflation with extra "fix missing includes" commits after the fact. But maybe that's not actually an issue in the grand scheme of things.


https://github.com/llvm/llvm-project/pull/143369