[libxml2] build: require automake-1.16.3 or later

[Nick Wellnhofer <nwellnhof src gnome org>]

commit df003c0aea767904c44de1bf420dc2a721347ad3
Author: Xi Ruoyao <xry111 xry111 site>
Date:   Fri Aug 26 10:09:13 2022 +0800

    build: require automake-1.16.3 or later
    
    We need
    https://git.savannah.gnu.org/cgit/automake.git/commit/?id=e21d46f
    to avoid an error like
    
        checking for PYTHON... no
        configure: error: Package requirements (python-3.1) were not met:
    
        No package 'python-3.1' found
    
    With python-3.10.
    
    Partially fixes #392.
    
    Note that there is another issue with python-3.10, like:
    
        checking for python... no
        checking for python2... no
        checking for python3... no
        checking for python3.9... no
        ...
        configure: error: no suitable Python interpreter found
    
    Fixing this one will need to require bumping automake version again, but
    the automake version containing this fix is not released yet.  And, this
    is rather minor because most environment has "python3" as a symlink to
    "python3.10" or whatever the latest python3.x installed.

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 161672f3..7badc57b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -39,7 +39,7 @@ AC_SUBST(LIBXML_VERSION_EXTRA)
 
 VERSION=${LIBXML_VERSION}
 
-AM_INIT_AUTOMAKE([1.15 foreign no-dist-gzip dist-xz])
+AM_INIT_AUTOMAKE([1.16.3 foreign no-dist-gzip dist-xz])
 AM_MAINTAINER_MODE([enable])
 AM_SILENT_RULES([yes])