patch 8.1.2138: including the build number in the Win32 binary is confusing

Problem:    Including the build number in the Win32 binary is confusing.
Solution:   Only use the patchlevel.
diff --git a/src/version.c b/src/version.c
index a6a1398..9cb3a01 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2138,
+/**/
     2137,
 /**/
     2136,