fix ip_hash on 64-bit platform

src/http/modules/ngx_http_upstream_ip_hash_module.c

diff --git a/src/http/modules/ngx_http_upstream_ip_hash_module.c b/src/http/modules/ngx_http_upstream_ip_hash_module.c
index 3ef4249..1c002e5 100644
--- a/src/http/modules/ngx_http_upstream_ip_hash_module.c
+++ b/src/http/modules/ngx_http_upstream_ip_hash_module.c
@@ -160,7 +160,7 @@
         p = hash % iphp->rrp.peers->number;
 
         n = p / (8 * sizeof(uintptr_t));
-        m = 1 << p % (8 * sizeof(uintptr_t));
+        m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
 
         if (!(iphp->rrp.tried[n] & m)) {