Do not send X-Powered-By if headers sent (#9039)

Co-authored-by: Eric Norris <erictnorris@gmail.com>

Author: bukka

main/main.c

@@ -1756,7 +1756,7 @@ zend_result php_request_startup(void)
 			CWDG(realpath_cache_size_limit) = 0;
 		}
 
-		if (PG(expose_php)) {
+		if (PG(expose_php) && !SG(headers_sent)) {
 			sapi_add_header(SAPI_PHP_VERSION_HEADER, sizeof(SAPI_PHP_VERSION_HEADER)-1, 1);
 		}
 

sapi/cgi/tests/bug69487.phpt

@@ -14,7 +14,5 @@ var_dump(strlen(file_get_contents('php://input')));
 Warning: Unknown: Unable to create temporary file, Check permissions in temporary files directory. in Unknown on line 0
 
 Warning: Unknown: POST data can't be buffered; all data discarded in Unknown on line 0
-
-Warning: Cannot modify header information - headers already sent in Unknown on line 0
 bool(false)
 int(0)

tests/basic/025.phpt

@@ -13,8 +13,6 @@ var_dump($_POST, $HTTP_RAW_POST_DATA);
 --EXPECTF--
 Warning: Unknown: POST Content-Length of 2050 bytes exceeds the limit of 1024 bytes in Unknown on line 0
 
-Warning: Cannot modify header information - headers already sent in Unknown on line 0
-
 Warning: Undefined variable $HTTP_RAW_POST_DATA in %s on line %d
 array(0) {
 }