url: don't compile detect_proxy if HTTP support is disabled
diff --git a/lib/url.c b/lib/url.c
index 5943896..f9c3242 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -4893,6 +4893,7 @@
   return FALSE;
 }
 
+#ifndef CURL_DISABLE_HTTP
 /****************************************************************
 * Detect what (if any) proxy to use. Remember that this selects a host
 * name and is not limited to HTTP proxies only.
@@ -4962,6 +4963,7 @@
 
   return proxy;
 }
+#endif /* CURL_DISABLE_HTTP */
 
 /*
  * If this is supposed to use a proxy, we need to figure out the proxy