patch 9.1.0622: MS-Windows: mingw-build can be optimized

Problem:  MS-Windows: mingw-build can be optimized
Solution: use --gc-sections to reduce the size of the executable
          (Ken Takata)

Use the --gc-sections linker option and the -ffunction-sections compiler
option to reduce the size of the executable files.  To make these work,
the -fno-asynchronous-unwind-tables compiler option is also needed.

This is enabled by default and can be disabled by `USE_GC_SECTIONS=no`.

Note: A similar feature has been already used in MSVC. (The /OPT linker
option.)

related: #15350

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 a70a978..01aea1f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    622,
+/**/
     621,
 /**/
     620,