Clarify docs for throwTo wrt atomicity (#8432)

Authored-by: Bertram Felgenhauer <bertram.felgenhauer@gmail.com>
Signed-off-by: Austin Seipp <aseipp@pobox.com>
Fix hangs with -threaded on iOS (#8307)

Authored-by: Luke Iannini <lukexi@me.com>
Signed-off-by: Austin Seipp <aseipp@pobox.com>