patch 8.1.1393: unnecessary type casts

Problem:    Unnecessary type casts.
Solution:   Remove type casts from alloc() and lalloc() calls. (Mike Williams)
diff --git a/src/os_win32.c b/src/os_win32.c
index 5bec2a2..6a832cf 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -7117,7 +7117,7 @@
 	return;
 
     /* Remember the buffer numbers for the arguments. */
-    fnum_list = (int *)alloc((int)sizeof(int) * GARGCOUNT);
+    fnum_list = (int *)alloc(sizeof(int) * GARGCOUNT);
     if (fnum_list == NULL)
 	return;		/* out of memory */
     for (i = 0; i < GARGCOUNT; ++i)