Fix warnings in PHP7 in gettext library

Not sure how to commit this upstream, the library seems to be
unmaintained.

inc/lib/gettext/streams.php

@@ -49,11 +49,15 @@ class StringReader {
   var $_pos;
   var $_str;
 
-  function StringReader($str='') {
+  function __construct($str='') {
     $this->_str = $str;
     $this->_pos = 0;
   }
 
+  function StringReader($str='') {
+    self::__construct($str);
+  }
+
   function read($bytes) {
     $data = substr($this->_str, $this->_pos, $bytes);
     $this->_pos += $bytes;
@@ -86,7 +90,7 @@ class FileReader {
   var $_fd;
   var $_length;
 
-  function FileReader($filename) {
+  function __construct($filename) {
     if (file_exists($filename)) {
 
       $this->_length=filesize($filename);
@@ -102,6 +106,10 @@ class FileReader {
     }
   }
 
+  function FileReader($filename) {
+    self::__construct($filename);
+  }
+
   function read($bytes) {
     if ($bytes) {
       fseek($this->_fd, $this->_pos);
@@ -143,7 +151,7 @@ class FileReader {
 // Preloads entire file in memory first, then creates a StringReader
 // over it (it assumes knowledge of StringReader internals)
 class CachedFileReader extends StringReader {
-  function CachedFileReader($filename) {
+  function __construct($filename) {
     if (file_exists($filename)) {
 
       $length=filesize($filename);
@@ -161,6 +169,10 @@ class CachedFileReader extends StringReader {
       return false;
     }
   }
+
+  function CachedFileReader($filename) {
+    self::__construct($filename);
+  }
 };