libdwfl: linux-pid-attach.c (pid_next_thread): Use rewinddir on first call.

dwfl_getthreads would otherwise fail to report any threads after it was
called once.

Reported-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Mark Wielaard <mjw@redhat.com>

libdwfl/ChangeLog

@@ -1,3 +1,8 @@
+2013-12-17  Mark Wielaard  <mjw@redhat.com>
+
+	* linux-pid-attach.c (pid_next_thread): Call rewinddir on first
+	traversal.
+
 2013-12-16  Mark Wielaard  <mjw@redhat.com>
 
 	* libdwfl.h (dwfl_module_getsymtab_first_global): New function

libdwfl/linux-pid-attach.c

@@ -164,6 +164,9 @@ pid_next_thread (Dwfl *dwfl __attribute__ ((unused)), void *dwfl_arg,
 {
   struct pid_arg *pid_arg = dwfl_arg;
   struct dirent *dirent;
+  /* Start fresh on first traversal. */
+  if (*thread_argp == NULL)
+    rewinddir (pid_arg->dir);
   do
     {
       errno = 0;