[RFA] Don't use thread_db on corefiles

[Daniel Jacobowitz <drow@mvista.com>]

This patch fixes a really frustrating internal error when you open the
coredump of a multithreaded application.  Depending on your kernel, either
the core has threads (corefile.c supports this just fine) or it doesn't. 
Neither way will opening libthread_db work right.

This patch isn't quite complete, because strange things happen when you
connect to a remote target too.  But fixing that requires a little more
fiddling.

Is this OK?

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer

2001-12-13  Daniel Jacobowitz  <drow@mvista.com>

	* thread-db.c (thread_db_new_objfile): Don't use thread_db on
	corefiles.

Index: thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/thread-db.c,v
retrieving revision 1.18
diff -u -r1.18 thread-db.c
--- thread-db.c	2001/10/13 15:04:02	1.18
+++ thread-db.c	2001/12/13 16:43:08
@@ -482,7 +482,9 @@
 {
   td_err_e err;
 
-  if (objfile == NULL)
+  /* Don't attempt to use thread_db on targets which can not run
+     (core files).  */
+  if (objfile == NULL || !target_has_execution)
     {
       /* All symbols have been discarded.  If the thread_db target is
          active, deactivate it now.  */