https://github.com/liblouis/liblouisxml/pull/3

commit 6c36457cf8de5816c7b85cb1eac4ba738547b841
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Sun Sep 8 11:29:35 2019 +0200

    Remove explicit detection of pkg-config
    
    PKG_CHECK_MODULES already does it, and with support for cross-compilation,
    so we should not try to detect pkg-config by hand, it only reduces support.

diff --git a/configure.ac b/configure.ac
index cbade97..df3baaa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -49,8 +49,6 @@ AM_PROG_LIBTOOL
 AC_CHECK_PROG([HELP2MAN], [help2man], [help2man])
 AM_CONDITIONAL([HAVE_HELP2MAN], [test x$HELP2MAN = xhelp2man])
 
-AC_PATH_PROG(PKG_CONFIG, pkg-config)
-
 PKG_CHECK_MODULES(BASE_DEPENDENCIES, [liblouis, libxml-2.0])
 
 # Checks for libraries.
