Sets os_should_swap_state() to true. Adds support for os_swap_context() twice in a row with the same state. Removes os_swap_context_go_native().
The api.detach test now passes on AArch64.
Enables all of the api.* and api.static_* tests for AArchXX, except api.startstop( crash) and api.static_prepop (hang) which will be fixed separately.
Fixes a build error in the api.static_crash test: a missing header.