[Auditor] Make the auditor multithreaded

[giordano]

Completely untested, but saving my progress for now. Let's see how far we get with this.

[giordano]

Good news: building locally JuliaPackaging/Yggdrasil#10479 (with hot ccache 🔥) goes from

[ Info: Timings: setup: 28.0s, build: 2m 14.22s, audit: 21m 23.27s, packaging: 12.44s

to

[ Info: Timings: setup: 27.72s, build: 2m 15.6s, audit: 8m 57.83s, packaging: 12.35s

when using 16 threads. Clearly scaling isn't ideal, but we have to put locks around all uses of the sanbox because otherwise it's a mess, but a 2x speedup is more than welcome.

Bad news: we need to put more locks around all logging macros because they aren't thread-safe and printing is messy, but hopefully they won't slow things down massively.

Note to self: we may be able to replace calls to patchelf at

BinaryBuilder.jl/src/auditor/soname_matching.jl

Line 74 in edecf34

set_soname_cmd = `$patchelf $(patchelf_flags(platform)) --set-soname $(soname) $(rel_path)`

and

BinaryBuilder.jl/src/auditor/dynamic_linkage.jl

Line 354 in edecf34

relink_cmd = `$patchelf $(patchelf_flags(platform)) --replace-needed $(old_libpath) $(libname) $(rel_path)`

with the JLL, which removes the need to use locks in a couple of places.

[giordano]

With Threads.@spawn instead of Threads.@threads I get marginally better timings, thanks to slightly more efficient load balancing (again with 16 julia threads):

[ Info: Timings: setup: 24.97s, build: 2m 7.83s, audit: 7m 27.03s, packaging: 12.16s

If CI is happy, this should be in a good shape.

Edit: sadly I had to revert this because it seems to introduce too many race conditions, especially in testing by capturing log messages. Better long-term solution is implementing #670 (have real "audit passes" objects which can be inspected for testing, rather than capturing logs in the ether, and also reorganise the passes to be more amenable to take advantage of parallelism), but here I'm trying to get basic threading working for the sake of making builds faster.

[giordano]

I see BB2 is already using patchelf, which is great: https://github.com/JuliaPackaging/BinaryBuilder2.jl/blob/54202516e430264dc6060f763c55a7f0fbbd542a/BinaryBuilderAuditor.jl/src/Scanning.jl#L1. But at a quick glance I don't see multi-threading enabled yet.

[giordano]

CI is happy now, let's see how it goes in production