merge revision(s) 5c7af72304d0ad33cd3f21b24a4bc44e8acd5b2c,d650b17686d49c2ce8e6a87039861154e93d4621: [Backport #18497]

	Assuming EXIT_SUCCESS equals 0 is not portable

	---
	 test/ruby/test_fiber.rb | 6 +++---
	 1 file changed, 3 insertions(+), 3 deletions(-)

	`rb_fiber_terminate` must not return [Bug #18497]

	In a forked process from a fiber, the fiber becomes the only
	fiber, `fiber_switch` does nothing as there is no other fibers,
	`rb_fiber_terminate` does not terminate the fiber.  In that case,
	reaches the end of `fiber_entry` finaly, which is declared as
	"COROUTINE" and should never return.
	---
	 cont.c                     |  3 ++-
	 eval_intern.h              |  2 +-
	 test/fiber/test_process.rb | 15 +++++++++++++++
	 test/ruby/test_fiber.rb    |  5 +++++
	 4 files changed, 23 insertions(+), 2 deletions(-)

1 files changed, 2 insertions, 1 deletions

diff --git a/cont.c b/cont.c
index 4b18ddda67..2d33ff4025 100644
--- a/cont.c
+++ b/cont.c
@@ -2039,7 +2039,7 @@ rb_fiber_set_scheduler(VALUE klass, VALUE scheduler)
     return rb_fiber_scheduler_set(scheduler);
 }
 
-static void rb_fiber_terminate(rb_fiber_t *fiber, int need_interrupt, VALUE err);
+NORETURN(static void rb_fiber_terminate(rb_fiber_t *fiber, int need_interrupt, VALUE err));
 
 void
 rb_fiber_start(rb_fiber_t *fiber)
@@ -2408,6 +2408,7 @@ rb_fiber_terminate(rb_fiber_t *fiber, int need_interrupt, VALUE error)
         fiber_switch(next_fiber, -1, &error, RB_NO_KEYWORDS, NULL, false);
     else
         fiber_switch(next_fiber, 1, &value, RB_NO_KEYWORDS, NULL, false);
+    ruby_stop(0);
 }
 
 static VALUE