g_needs_dynamic_alloc
Internal Emscripten thread-local wasm global.
Signal that the current thread is non to use the primary/static TLS region. Once this gets set it forces that all future calls to emscripten_tls_init to dynamically allocate TLS. If this global is true then TLS needs to be dyanically allocated, if its false we are free to use the existing/global __tls_base.
Initialized in _emscripten_tls_init