patch 8.1.0931: vtp_working included in GUI build but unused

Problem:    vtp_working included in GUI build but unused.
Solution:   Adjust #ifdefs. (Ken Takata, closes #3971)
diff --git a/src/os_win32.c b/src/os_win32.c
index 0680346..816c3a5 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -186,12 +186,12 @@
 static int win32_setattrs(char_u *name, int attrs);
 static int win32_set_archive(char_u *name);
 
-static int vtp_working = 0;
 static int conpty_working = 0;
 static int conpty_stable = 0;
 static void vtp_flag_init();
 
 #ifndef FEAT_GUI_W32
+static int vtp_working = 0;
 static void vtp_init();
 static void vtp_exit();
 static int vtp_printf(char *format, ...);
@@ -7874,14 +7874,14 @@
     return T_NAME != NULL && STRCMP(T_NAME, "win32") == 0;
 }
 
-#endif
-
     int
 has_vtp_working(void)
 {
     return vtp_working;
 }
 
+#endif
+
     int
 has_conpty_working(void)
 {
diff --git a/src/version.c b/src/version.c
index e2b6f7a..00c63e5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    931,
+/**/
     930,
 /**/
     929,