https://github.com/dajobe/raptor/commit/3f9335b3cfd945a8d5f6f75f87cab04c53cc2b6d

From 3f9335b3cfd945a8d5f6f75f87cab04c53cc2b6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andreas=20M=C3=BCller?= <schnitzeltony@googlemail.com>
Date: Tue, 27 Oct 2015 10:35:35 +0100
Subject: [PATCH] configure.ac: do additional checks on libxml2 when library is
 found
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In yocto cross environments we must use pkg-config. Configuring with

  --without-xml2-config
  --without-curl-config

causes

| checking for LIBXML... yes
| checking for libxml via pkg-config... yes - 2.9.2
| checking for LIBCURL... yes
| checking for libcurl via pkg-config... yes - 7.44.0
| checking for ICU... no
| checking for yajl installation... not found. Get it from http://lloyd.github.com/yajl/ and use --with-yajl=DIR if necessary to configure the installation directory.
| checking GRDDL parser requirements... no - libxml2 and libxslt are both not available

Applying this patch fixes configuration.

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
--- a/configure.ac
+++ b/configure.ac
@@ -599,7 +599,7 @@ have_libxml=0
 need_libxml=0
 
 oCPPFLAGS="$CPPFLAGS"
-if test "X$XML_CONFIG" != X; then
+if test "X$libxml_source" != X; then
   CPPFLAGS="$LIBXML_CFLAGS $CPPFLAGS"
   LIBS="$LIBS $LIBXML_LIBS"
   AC_CHECK_FUNC(xmlCreatePushParserCtxt, have_xmlCreatePushParserCtxt=yes, have_xmlCreatePushParserCtxt=no)