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/search.c b/src/search.c
index 313892f..20e619d 100644
--- a/src/search.c
+++ b/src/search.c
@@ -1429,7 +1429,7 @@
 		// Reserve enough space for the search pattern + offset.
 		len = STRLEN(p) + off_len + 3;
 
-	    msgbuf = alloc((int)len);
+	    msgbuf = alloc(len);
 	    if (msgbuf != NULL)
 	    {
 		vim_memset(msgbuf, ' ', len);