thread_pthread.c: check stack on co-routine case

* thread_pthread.c (ruby_init_stack): check stack bounds even if
  get_main_stack succeeded, on the "co-routine" case.
  https://github.com/ruby/ruby/commit/53953ee#commitcomment-18887413

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56060 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sat Sep  3 11:28:29 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* thread_pthread.c (ruby_init_stack): check stack bounds even if
+	  get_main_stack succeeded, on the "co-routine" case.
+	  https://github.com/ruby/ruby/commit/53953ee#commitcomment-18887413
+
 Fri Sep  2 16:06:59 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* internal.h (MEMO_V1_SET, MEMO_V2_SET): fix typos.  use the macro

thread_pthread.c

@@ -749,7 +749,7 @@ ruby_init_stack(volatile VALUE *addr
 	    native_main_thread.stack_maxsize = size;
 	    native_main_thread.stack_start = stackaddr;
 	    reserve_stack(stackaddr, size);
-	    return;
+	    goto bound_check;
 	}
     }
 #endif
@@ -797,6 +797,9 @@ ruby_init_stack(volatile VALUE *addr
 #endif
     }
 
+#if MAINSTACKADDR_AVAILABLE
+  bound_check:
+#endif
     /* If addr is out of range of main-thread stack range estimation,  */
     /* it should be on co-routine (alternative stack). [Feature #2294] */
     {