Fix crashes when unbind_for_thread_switch signals an error.

 src/eval.c (unbind_for_thread_switch): Accept a 'struct
 thread_state *' argument and use specpdl_ptr and specpdl of that
 thread.  Fixes crashes if find_symbol_value signals an error.
 src/thread.c (post_acquire_global_lock): Update current_thread
 before calling unbind_for_thread_switch.  Pass the previous thread
 to unbind_for_thread_switch.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/eval.c b/src/eval.c
index 68a3691ad9b..b8a61590387 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3484,11 +3484,11 @@ unbind_to (ptrdiff_t count, Lisp_Object value)
 }
 
 void
-unbind_for_thread_switch (void)
+unbind_for_thread_switch (struct thread_state *thr)
 {
   union specbinding *bind;
 
-  for (bind = specpdl_ptr; bind != specpdl; --bind)
+  for (bind = thr->m_specpdl_ptr; bind != thr->m_specpdl; --bind)
     {
       if (bind->kind >= SPECPDL_LET)
         {