patch 8.1.0727: compiler warning for sprintf() argument

Problem:    Compiler warning for sprintf() argument.
Solution:   Add type cast.
diff --git a/src/dosinst.c b/src/dosinst.c
index 5c290a8..5b05598 100644
--- a/src/dosinst.c
+++ b/src/dosinst.c
@@ -473,7 +473,7 @@
     for (i = 0; ; i++)
     {
 	sprintf(temp_uninst, "%s\\vimun%04X.exe", temp_dir,
-							(i + tick) & 0xFFFF);
+					  (unsigned int)((i + tick) & 0xFFFF));
 	if (CopyFile(uninst_exe, temp_uninst, TRUE))
 	    break;
 	if (GetLastError() != ERROR_FILE_EXISTS)