patch 9.1.0959: Coverity complains about type conversion

Problem:  Coverity complains about type conversion
          (after v9.1.0957)
Solution: use size_t instead of int for file length
          (Yegappan Lakshmanan)

closes: #16297

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/option.c b/src/option.c
index e4c52bd..52f9969 100644
--- a/src/option.c
+++ b/src/option.c
@@ -8452,7 +8452,7 @@
 		    }
 #endif
 		    else
-			(void)modify_fname((char_u *)":h", FALSE, &usedlen, &p, &fbuf, (int *)&len);
+			(void)modify_fname((char_u *)":h", FALSE, &usedlen, &p, &fbuf, &len);
 
 		    if (p != NULL)
 		    {