Racy bitcode compilation

[maleadt]

I thought we already worked around this, using an atomic move-in-place:

GPUCompiler.jl/src/rtlib.jl

Lines 145 to 149 in c15433c

	# atomic write to disk
	temp_path, io = mktemp(dirname(path); cleanup=false)
	write(io, lib)
	close(io)
	Base.rename(temp_path, path; force=true)

However, it looks like this still happens on CI, e.g. https://buildkite.com/julialang/metal-dot-jl/builds/947#018ee3aa-18e2-472c-b93f-f77451e3f87a

[maleadt]

Here's another instance: https://buildkite.com/julialang/cuda-dot-jl/builds/5180#018fb96f-180e-42ad-b06a-559061791f12

I'm actually not sure where this (fatal) error comes from, as LLVM.jl already seems to handle it gracefully:

julia> LLVM.Context() do ctx parse(LLVM.Module, read("wip.jl")) end
ERROR: LLVM error: Invalid bitcode signature
Stacktrace:
 [1] handle_diagnostic(diag_ref::Ptr{LLVM.API.LLVMOpaqueDiagnosticInfo}, args::Ptr{Nothing})
   @ LLVM ~/Julia/pkg/LLVM/src/core/context.jl:134
 [2] LLVMParseBitcodeInContext2(ContextRef::Context, MemBuf::MemoryBuffer, OutModule::Base.RefValue{Ptr{…}})
   @ LLVM.API ~/Julia/pkg/LLVM/lib/15/libLLVM.jl:185