https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=182116

exec() causes fatal:
	Cannot find user-level thread for LWP 4256: generic error
Patch below does not enable the new process tracing but it will not crash.
MAY_FOLLOW_EXEC enable for GNU/Linux was discouraged by Daniel Jacobowitz.
	<20060721184421.GA22820@nevyn.them.org>


Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-thread-db.c,v
retrieving revision 1.17
diff -u -p -r1.17 linux-thread-db.c
--- linux-thread-db.c	18 Jul 2006 22:53:20 -0000	1.17
+++ linux-thread-db.c	22 Jul 2006 12:17:50 -0000
@@ -875,6 +875,14 @@ thread_db_wait (ptid_t ptid, struct targ
   if (ourstatus->kind == TARGET_WAITKIND_EXITED)
     return pid_to_ptid (-1);
 
+  if (ourstatus->kind == TARGET_WAITKIND_EXECD)
+    {
+      unpush_target (&thread_db_ops);
+      using_thread_db = 0;
+
+      return pid_to_ptid (GET_PID (ptid));
+    }
+
   if (ourstatus->kind == TARGET_WAITKIND_STOPPED
       && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
     /* Check for a thread event.  */