curl: point out unnecessary uses of -X in verbose mode

It uses 'Note:' as a prefix as opposed to the common 'Warning:' to take
down the tone a bit.

It adds a warning for using -XHEAD on other methods becasue that may
lead to a hanging connection.

src/tool_helpers.c

@@ -89,3 +89,26 @@ int SetHTTPrequest(struct OperationConfig *config, HttpReq req, HttpReq *store)
 
   return 1;
 }
+
+void customrequest_helper(struct OperationConfig *config, HttpReq req,
+                          char *method)
+{
+  /* this mirrors the HttpReq enum in tool_sdecls.h */
+  const char *dflt[]= {
+    "GET",
+    "GET",
+    "HEAD",
+    "POST",
+    "POST"
+  };
+
+  if(curl_strequal(method, dflt[req])) {
+    notef(config->global, "Unnecessary use of -X or --request, %s is already "
+          "inferred.\n", dflt[req]);
+  }
+  else if(curl_strequal(method, "head")) {
+    warnf(config->global,
+          "Setting custom HTTP method to HEAD may not work the way you "
+          "want.\n");
+  }
+}