https://bugs.gentoo.org/751922
https://gitlab.gnome.org/GNOME/libxml2/-/issues/202

From c1bae734f3850f6900cf54d186ca0a9102895d82 Mon Sep 17 00:00:00 2001
From: Lars Wendler <polynomial-c@gentoo.org>
Date: Fri, 30 Oct 2020 10:27:23 +0100
Subject: [PATCH] Fix build with icu-68.1

icu-68.1 removed macro definitions for TRUE and FALSE

Signed-off-by: Lars Wendler <polynomial-c@gentoo.org>
---
--- a/encoding.c
+++ b/encoding.c
@@ -1958,7 +1958,7 @@ xmlEncOutputChunk(xmlCharEncodingHandler *handler, unsigned char *out,
 #ifdef LIBXML_ICU_ENABLED
     else if (handler->uconv_out != NULL) {
         ret = xmlUconvWrapper(handler->uconv_out, 0, out, outlen, in, inlen,
-                              TRUE);
+                              1);
     }
 #endif /* LIBXML_ICU_ENABLED */
     else {
--