Merge branch 'PHP-7.3' into PHP-7.4

* PHP-7.3:
  Fix #77700: Writing truecolor images as GIF ignores interlace flag

Author: cmb69

ext/gd/libgd/gd_gif_out.c

@@ -144,7 +144,7 @@ static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
 	BitsPerPixel = colorstobpp(tim->colorsTotal);
 	/* All set, let's do it. */
 	GIFEncode(
-		out, tim->sx, tim->sy, tim->interlace, 0, tim->transparent, BitsPerPixel,
+		out, tim->sx, tim->sy, interlace, 0, tim->transparent, BitsPerPixel,
 		tim->red, tim->green, tim->blue, tim);
 	if (pim) {
 		/* Destroy palette based temporary image. */

ext/gd/tests/bug77700.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Bug #77700 (Writing truecolor images as GIF ignores interlace flag)
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die('skip gd extension not available');
+?>
+--FILE--
+<?php
+$im = imagecreatetruecolor(10, 10);
+imagefilledrectangle($im, 0, 0, 9, 9, imagecolorallocate($im, 255, 255, 255));
+imageinterlace($im, 1);
+imagegif($im, __DIR__ . 'bug77700.gif');
+
+$im = imagecreatefromgif(__DIR__ . 'bug77700.gif');
+var_dump(imageinterlace($im));
+?>
+===DONE===
+--EXPECT--
+int(1)
+===DONE===
+--CLEAN--
+<?php
+unlink(__DIR__ . 'bug77700.gif');
+?>