[libxml2] Support custom prefix when installing Python module

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 85a35ba068c7b4e639bbe01db1e09263d910199c
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Mon Feb 14 17:44:29 2022 +0100

    Support custom prefix when installing Python module
    
    Also fixes make distcheck.

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 86d84625..9b458093 100644
--- a/configure.ac
+++ b/configure.ac
@@ -876,7 +876,7 @@ if test "$with_python" != "no" ; then
            then
                PYTHON_SITE_PACKAGES=$with_python/lib/site-packages
            else
-               PYTHON_SITE_PACKAGES=`$PYTHON -c "from distutils import sysconfig; 
print(sysconfig.get_python_lib())"`
+               PYTHON_SITE_PACKAGES=$($PYTHON -c 'from distutils import sysconfig; 
print(sysconfig.get_python_lib(True,False,"${exec_prefix}"))')
            fi
        fi
     fi