rtems-debugger-threads.c: Three Dereference before null check errors spotted by Coverity

[Ryan Long]

CID 1468681: Dereference before null check in rtems_debugger_thread_continue().
CID 1468690: Dereference before null check in rtems_debugger_thread_system_resume().
CID 1468694: Dereference before null check in rtems_debugger_thread_find_index().

430  rtems_debugger_threads* threads = rtems_debugger->threads;
431  rtems_debugger_thread*  current;
432  int                     r = 0;
   deref_ptr_in_call: Dereferencing pointer threads. [show details]
433  current = rtems_debugger_thread_current(threads);
   CID 1468681 (#1 of 1): Dereference before null check (REVERSE_INULL)check_after_deref: Null-checking threads suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
434  if (threads != NULL && current != NULL) {

347  rtems_debugger_threads* threads = rtems_debugger->threads;
348  rtems_debugger_thread*  current;
349  int                     r = 0;
   deref_ptr_in_call: Dereferencing pointer threads. [show details]
350  current = rtems_debugger_thread_current(threads);
   CID 1468690 (#1 of 1): Dereference before null check (REVERSE_INULL)check_after_deref: Null-checking threads suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
351  if (threads != NULL && current != NULL) {

150  rtems_debugger_threads* threads = rtems_debugger->threads;
   deref_ptr_in_call: Dereferencing pointer threads. [show details]
151  rtems_debugger_thread*  current = rtems_debugger_thread_current(threads);
152  int                     r = -1;
   CID 1468694 (#1 of 1): Dereference before null check (REVERSE_INULL)check_after_deref: Null-checking threads suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
153  if (threads != NULL) {

[Ryan Long <ryan.long@…>]

In [changeset:"f65d3384dd923c9ead9bcf264592bd879054f6dc/rtems" f65d3384/rtems]:

rtems-debugger-threads.c: Fix three Dereference before null check errors

CID 1468681: Dereference before null check in rtems_debugger_thread_continue().
CID 1468690: Dereference before null check in rtems_debugger_thread_system_resume().
CID 1468694: Dereference before null check in rtems_debugger_thread_find_index().

Closes #4241.