patch 8.1.1386: unessesary type casts for lalloc()

Problem:    Unessesary type casts for lalloc().
Solution:   Remove type casts.  Change lalloc(size, TRUE) to alloc(size).
diff --git a/src/os_mswin.c b/src/os_mswin.c
index 67989fe..6f3e708 100644
--- a/src/os_mswin.c
+++ b/src/os_mswin.c
@@ -890,7 +890,7 @@
 	else if (retval_str != NULL
 		&& (len = check_str_len(retval_str)) > 0)
 	{
-	    *string_result = lalloc((long_u)len, TRUE);
+	    *string_result = alloc(len);
 	    if (*string_result != NULL)
 		mch_memmove(*string_result, retval_str, len);
 	}