patch 9.1.0628: MinGW: coverage files are not cleaned up

Problem:  MinGW: coverage files are not cleaned up
Solution: Adjust clean rule to remove the coverage files
          (Ken Takata)

closes: #15361

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 d6f8085..f2b7a19 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    628,
+/**/
     627,
 /**/
     626,