Keep the rest of the runtime's statics alive through exit #371

#67 made the GC's statics immortal, allocated once and never destroyed, so a thread still running when main returns or Sys.exit is called cannot use them after their destructors run. HaxeFoundation/hxcpp#1433 proposes the same for stock hxcpp behind an opt-in define, HXCPP_IMMORTAL_STATICS, and covers more of the runtime than #67 did.

Its repro, a worker filling an ObjectMap while main returns, does not crash libhxcpp: 0 in 200 runs on Windows x64 at 299cff6b. The object id map it reaches is one #67 already made immortal, and libhxcpp's ObjectMap hashes keys by address when objects do not move, so it does not reach that map at all. The PR reports most of its crashes on macOS, which I have not run.

But libhxcpp still has statics outside the GC with exit-time destructors, which a thread still running at exit can use after they are destroyed:

• sModuleLock in src/hx/cppia/CppiaModule.cpp, taken when a cppia module loads or releases
• sYoungValueLock in src/hx/gc/Immix.cpp, added for Track dirty pointer-array ranges to reduce minor GC work after sparse writes #301 and Avoid scanning entire old maps after sparse writes during minor GC #305: hx::FastMutex is an SRW lock on Windows, but std::mutex elsewhere, so it is destroyed at exit while another thread's write barrier can still take it
• the kind maps sgKindMap and sgReverseKindMap, and the mutex beside them, in src/hx/CFFI.cpp
• sLoadedMap, sgLoadedModule, sgOrderedModules, sgLibPath, sgLastLoadError and the loader's recursive mutex in src/hx/Lib.cpp
• sVarIdNameMap in src/hx/cppia/CppiaVars.cpp
• the environment mutex in src/hx/libs/std/Sys.cpp
• initReturnBuffer in src/hx/StdLibs.cpp and sgResultBuffer in src/hx/RunLibs.cpp
• the profiler, telemetry and Tracy mutexes, maps and lists, in builds with those enabled

As with #67 and the GC's statics, these should become immortal unconditionally rather than behind a define: they live until the process ends anyway, so never destroying them costs nothing. Where a static is used from a static initializer, as the CFFI kind maps can be through hxcpp_kind_share, it should be made on first use, as the PR does.

To do:

• Make each of these allocated once and never destroyed, or created on first use where static initialization order matters.
• Add a regression test that keeps a worker using these paths (cppia module loading, CFFI kinds, library loading, environment access) while main returns, run many times over.
• Check with clang's -Wexit-time-destructors that nothing else in the runtime is destroyed at exit.

Related: HaxeFoundation/hxcpp#1433, #67.