2015-12-28  John David Anglin  <danglin@gcc.gnu.org>

	PR libfortran/68744
	* runtime/backtrace.c: Include gthr.h.
	(show_backtrace): Use __gthread_active_p() to determine whether threads
	are active.  Return if lbstate is NULL.

Index: runtime/backtrace.c
===================================================================
--- runtime/backtrace.c	(revision 231814)
+++ runtime/backtrace.c	(working copy)
@@ -24,6 +24,8 @@
 
 #include "libgfortran.h"
 
+#include <gthr.h>
+
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
@@ -137,8 +139,12 @@
   struct backtrace_state *lbstate;
   struct mystate state = { 0, false, in_signal_handler };
  
-  lbstate = backtrace_create_state (NULL, 1, error_callback, NULL);
+  lbstate = backtrace_create_state (NULL, __gthread_active_p (),
+				    error_callback, NULL);
 
+  if (lbstate == NULL)
+    return;
+
   if (!BACKTRACE_SUPPORTED || (in_signal_handler && BACKTRACE_USES_MALLOC))
     {
       /* If symbolic backtrace is not supported on this target, or would