Fix #77943: imageantialias($image, false); does not work

Firstly, we must not call `gdImageSetAntiAliased()` (which sets the
color to anti-alias), but rather modify the `gdImage.AA` flag.
Furthermore, we have to actually use the supplied boolean value.

We also make sure that we don't attempt to enable anti-aliasing for
palette images.

Author: cmb69

NEWS

@@ -5,6 +5,9 @@ PHP                                                                        NEWS
 - FPM:
   . Fixed bug #77921 (static.php.net doesn't work anymore). (Peter Kokot)
 
+- GD:
+  . Fixed bug #77943 (imageantialias($image, false); does not work). (cmb)
+
 - JSON:
   . Fixed bug #77843 (Use after free with json serializer). (Nikita)
 

ext/gd/gd.c

@@ -4699,7 +4699,11 @@ PHP_FUNCTION(imageantialias)
 	if ((im = (gdImagePtr)zend_fetch_resource(Z_RES_P(IM), "Image", le_gd)) == NULL) {
 		RETURN_FALSE;
 	}
-	gdImageSetAntiAliased(im, 0);
+
+	if (im->trueColor) {
+		im->AA = alias;
+	}
+
 	RETURN_TRUE;
 }
 /* }}} */