patch 8.1.1232: can't build on MS-Windows

Problem:    Can't build on MS-Windows.
Solution:   Define process_still_running.
diff --git a/src/version.c b/src/version.c
index 80ee7fb..40bcf89 100644
--- a/src/version.c
+++ b/src/version.c
@@ -768,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1232,
+/**/
     1231,
 /**/
     1230,