patch 9.1.0621: MS-Windows: startup code can be improved

Problem:  MS-Windows: startup code can be improved
Solution: Re-work and optimize win32 startup code
          (Ken Takata)

* Revise the code and reduce #ifdefs.
* For VIMDLL, stop using the default CRT startup code to reduce the file
  size.
  The file size becomes ~130 KB -> ~34 KB on MSVC.
* Update comments. Make them consistent between os_w32dll.c and
  os_w32exe.c.

closes: #15352

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 806e3c5..a70a978 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    621,
+/**/
     620,
 /**/
     619,