fork error when trying to call VirtualAlloc with size==0

[Yuyi Wang]

I tried dlfork(FORK_NO_RELOAD) after dlopen() the proc macro DLLs. Now rustc
works as expected. Therefore, I think the problem is most likely caused by too
many DLLs loaded. See the PR here: https://github.com/rust-lang/rust/pull/141276

I think dlfork is a good workaround, but not the best. It would be better if we
can set a specific DLL not reload on fork on dlopen(). What do you think?

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Yuyi Wang