patch 8.1.1415: build error in MS-Windows GUI

Problem:    Build error in MS-Windows GUI.
Solution:   Fix the LALLOC_MULT() argument.
diff --git a/src/gui_w32.c b/src/gui_w32.c
index 0f683b8..5600ac0 100644
--- a/src/gui_w32.c
+++ b/src/gui_w32.c
@@ -6056,7 +6056,7 @@
 
 	/* Don't give an out-of-memory message here, it would call us
 	 * recursively. */
-	padding = LALLOC_MULT(sizeof(int), pad_size);
+	padding = LALLOC_MULT(int, pad_size);
 	if (padding != NULL)
 	    for (i = 0; i < pad_size; i++)
 		padding[i] = gui.char_width;