Threaded modules need to execute `data.drop` on all threads

In the description of the passive segments portion of linking it mentions that __wasm_init_memory will be used to initialize all memory segments. This is presumably called on the first thread, and LLD today also executes data.drop for each memory segment.

I think, though, that all new threads also need to execute data.drop for all memory segments to avoid keeping them around, right? Should data.drop not be part of __wasm_init_memory? Or perhaps another synthetic function to drop segments?

FWIW we've had a strategy of doing this in wasm-bindgen prior to LLVM 9 which involved injecting a start function which did an atomic add to initialize a thread id counter, and based off the thread ID it'd initialize memory or drop segments. I wonder if perhaps most modules need something like that anyway to get synthesized during LLD as well?