ext/curl: Add CURLINFO_POSTTRANSFER_TIME_T support

libcurl ref: [`CURLINFO_POSTTRANSFER_TIME_T`](https://curl.se/libcurl/c/CURLINFO_POSTTRANSFER_TIME_T.html)

`CURLINFO_POSTTRANSFER_TIME_T` is a libcurl info option that returns
the time it took to "post" the transfer. Available since libcurl 8.10.0

This value is also exposed as `posttransfer_time_us` in the
`curl_getinfo()` return value when the `$option` parameter is not
passed.

Author: Ayesh

UPGRADING

@@ -298,6 +298,11 @@ PHP 8.4 UPGRADE NOTES
     to allow or abort the request.
   . Added CURLOPT_SERVER_RESPONSE_TIMEOUT, which was formerly known as
     CURLOPT_FTP_RESPONSE_TIMEOUT. Both constants hold the same value.
+  . curl_getinfo() function now returns "posttransfer_time_us", containing the
+    number of microseconds from the start until the last byte is sent. When a
+    redirect is followed, the time from each request is added together. This
+    value can also be retrieved by passing CURLINFO_POSTTRANSFER_TIME_T to the
+    curl_getinfo() $option parameter. This requires libcurl 8.10.0 or later.
 
 - Date:
   . Added static methods
@@ -1028,6 +1033,7 @@ PHP 8.4 UPGRADE NOTES
   . CURL_PREREQFUNC_OK.
   . CURL_PREREQFUNC_ABORT.
   . CURLOPT_SERVER_RESPONSE_TIMEOUT.
+  . CURLINFO_POSTTRANSFER_TIME_T.
 
 - Intl:
   . The IntlDateFormatter class exposes now the new PATTERN constant

ext/curl/curl.stub.php

@@ -3012,6 +3012,13 @@
  * @cvalue CURLINFO_TOTAL_TIME_T
  */
 const CURLINFO_TOTAL_TIME_T = UNKNOWN;
+#if LIBCURL_VERSION_NUM >= 0x080a00 /* Available since 8.10.0 */
+/**
+ * @var int
+ * @cvalue CURLINFO_POSTTRANSFER_TIME_T
+ */
+const CURLINFO_POSTTRANSFER_TIME_T = UNKNOWN;
+#endif
 /**
  * @var int
  * @cvalue CURLOPT_DISALLOW_USERNAME_IN_URL

ext/curl/curl_arginfo.h

@@ -2557,6 +2557,11 @@ PHP_FUNCTION(curl_getinfo)
 		if (curl_easy_getinfo(ch->cp, CURLINFO_STARTTRANSFER_TIME_T, &co) == CURLE_OK) {
 			CAAL("starttransfer_time_us", co);
 		}
+#if LIBCURL_VERSION_NUM >= 0x080a00 /* Available since 8.10.0 */
+		if (curl_easy_getinfo(ch->cp, CURLINFO_POSTTRANSFER_TIME_T, &co) == CURLE_OK) {
+			CAAL("posttransfer_time_us", co);
+		}
+#endif
 		if (curl_easy_getinfo(ch->cp, CURLINFO_TOTAL_TIME_T, &co) == CURLE_OK) {
 			CAAL("total_time_us", co);
 		}

ext/curl/interface.c

@@ -0,0 +1,41 @@
+--TEST--
+Curlinfo CURLINFO_POSTTRANSFER_TIME_T
+--EXTENSIONS--
+curl
+--SKIPIF--
+<?php
+$curl_version = curl_version();
+if ($curl_version['version_number'] < 0x080a00) die("skip: test works only with curl >= 8.10.0");
+?>
+--FILE--
+<?php
+include 'server.inc';
+
+$host = curl_cli_server_start();
+$port = (int) (explode(':', $host))[1];
+
+$ch = curl_init();
+curl_setopt($ch, CURLOPT_URL, "{$host}/get.inc?test=file");
+curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
+
+$info = curl_getinfo($ch);
+var_dump(isset($info['posttransfer_time_us']));
+var_dump($info['posttransfer_time_us'] === 0); // this is always 0 before executing the transfer
+
+$result = curl_exec($ch);
+
+$info = curl_getinfo($ch);
+var_dump(isset($info['posttransfer_time_us']));
+var_dump(is_int($info['posttransfer_time_us']));
+var_dump(curl_getinfo($ch, CURLINFO_POSTTRANSFER_TIME_T) === $info['posttransfer_time_us']);
+var_dump(curl_getinfo($ch, CURLINFO_POSTTRANSFER_TIME_T) > 0);
+
+?>
+--EXPECT--
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+