Fix compiler warning for misleading guarding in the tkinter (GH-26244)

The newest gcc emmits this warning:

```
/Modules/_tkinter.c:272:9: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
  272 |         if(tcl_lock)PyThread_acquire_lock(tcl_lock, 1); tcl_tstate = tstate; }
      |         ^~
/Modules/_tkinter.c:2869:5: note: in expansion of macro ‘LEAVE_PYTHON’
 2869 |     LEAVE_PYTHON
      |     ^~~~~~~~~~~~
/Modules/_tkinter.c:243:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
  243 |     (*(PyThreadState**)Tcl_GetThreadData(&state_key, sizeof(PyThreadState*)))
      |     ^
/Modules/_tkinter.c:272:57: note: in expansion of macro ‘tcl_tstate’
  272 |         if(tcl_lock)PyThread_acquire_lock(tcl_lock, 1); tcl_tstate = tstate; }
      |                                                         ^~~~~~~~~~
/Modules/_tkinter.c:2869:5: note: in expansion of macro ‘LEAVE_PYTHON’
 2869 |     LEAVE_PYTHON

```

that's because the macro packs together two statements at the same level
as the "if". The warning is misleading but is very noisy so it makes
sense to fix it.