patch 8.2.0273: MS-Windows uninstall may delete wrong batch file

Problem:    MS-Windows uninstall may delete wrong batch file.
Solution:   Add specific marker in the generated batch file. (Ken Takata,
            closes #5654)
diff --git a/src/dosinst.h b/src/dosinst.h
index a849dad..c262c42 100644
--- a/src/dosinst.h
+++ b/src/dosinst.h
@@ -354,6 +354,9 @@
 					"vimtutor.bat",  "vimtutor.bat", ""},
 };
 
+/* Uninstall key for vim.bat, etc. */
+#define VIMBAT_UNINSTKEY    "rem # uninstall key: " VIM_VERSION_NODOT " #"
+
 #define ICON_COUNT 3
 char *(icon_names[ICON_COUNT]) =
 	{"gVim " VIM_VERSION_SHORT,