Add ThreadSanitzer hooks for jl_mutex_t

[xal-0]

Lets us detect lock order inversions on jl_mutex_ts, races on mutex initialization, and shows the list of locked mutexes when some other ThreadSanitizer warning is shown.

[vchuravy]

Very cool! Would it make sense to also push this into user code, so that the locks written in Julia code support this?

[xal-0]

That's the plan, though it will require some codegen hacks to make everything bootstrap fast enough. If the decision to include the call to the hooks is made in Julia, we won't easily be able to cross compile the sysimage from a non-tsan version of Julia.

[vchuravy]

Can we put it in build_h.jl(

julia/base/Makefile

Line 84 in 3b29187

@printf "%s\n" "const BUILD_TRIPLET = \"$(BB_TRIPLET_LIBGFORTRAN_CXXABI)\"" >> $@

)? Or is the cross-compile going to use the one from the "host"?