bpo-35177, Python-ast.h: Fix "Yield" compiler warning (GH-10664)

Partially revert commit 5f2df88b63e50d23914e97ec778861a52abdeaad:
add "#undef Yield" to .c files after including Python-ast.h.

Fix the warning:

    winbase.h(102): warning C4005: 'Yield': macro redefinition
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 58e1647..af3d5ef 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -3,6 +3,7 @@
 #include "Python.h"
 
 #include "Python-ast.h"
+#undef Yield   /* undefine macro conflicting with <winbase.h> */
 #include "pycore_context.h"
 #include "pycore_hamt.h"
 #include "pycore_pathconfig.h"