https://bugs.winehq.org/show_bug.cgi?id=38886
--- Comment #22 from Patrick Littlefighter1996@googlemail.com --- I've used the target system to build wine and now it's working as intended. I've noticed, all DLLs appear to be wrappers in the broken build (they are usually about 2550 bytes), while in the working build, it's the other way around.
On Ubuntu (through WSL) such a similar build (with small DLLs, probably wrappers around .so files), works just fine.
I suspect that this other (build-related) issue somehow manifests as this (varargs) issue.
I'm unsure if I should open an issue about this or not. Sound more like something that would belong in forums, if it was an issue specific to my toolchain.