other. Ensure headers in include/ can be included in any order
(except for econfig-spec.h, which is special). New header types.h to
help avoid inclusion cycles. Sort include directives. Remove some
superflous includes.
(empth_wait_for_shutdown): New.
(main): Use it to wait for shutdown signal, then shut down. Closes
#770492.
(empth_exit): Remove the weird special case for main thread.
Implement empth_wait_for_shutdown() for EMPTH_LWP:
[EMPTH_LWP] (lwpInitSigWait, lwpSigWait, lwpSigWakeup): New.
Declaration of lwpSigWait was accidentally committed in the previous
revision of lwp.h.
[EMPTH_LWP] (lwpInitSystem): New parameter waitset, pass it on to
lwpInitSigWait().
[EMPTH_LWP] (lwpReschedule): Call lwpSigWakeup().
[EMPTH_LWP] (empth_init): Declare signals needed by
empth_wait_for_shutdown().
(empth_wait_for_shutdown): Implement on top of lwpSigWait().
Implement empth_wait_for_shutdown() for EMPTH_POSIX:
[EMPTH_POSIX] (empth_init): Block signals, so that
empth_wait_for_shutdown() can use sigwait() safely.
(empth_wait_for_shutdown): Implement on top of sigwait().
Implement empth_wait_for_shutdown() for EMPTH_W32:
(empth_wait_for_shutdown): Implement on top of loc_BlockMainThread().
