[libxml2] CMakeLists.txt: Fix LIBXML_VERSION_NUMBER

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 94ac5e61f399759a5463c0505099222ed8f13a82
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu Apr 7 02:05:41 2022 +0200

    CMakeLists.txt: Fix LIBXML_VERSION_NUMBER
    
    Also fix LIBXML_VERSION and remove LIBXML_VERSION_STRING.
    
    Fixes #365.

 CMakeLists.txt | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 68419a09..075d5cde 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -104,10 +104,13 @@ foreach(VARIABLE IN ITEMS WITH_AUTOMATA WITH_C14N WITH_CATALOG WITH_DEBUG WITH_E
        endif()
 endforeach()
 
-set(LIBXML_VERSION ${LIBXML_MAJOR_VERSION}0${LIBXML_MINOR_VERSION}0${LIBXML_MICRO_VERSION})
-set(LIBXML_VERSION_STRING "${LIBXML_VERSION}")
+set(LIBXML_VERSION ${VERSION})
 set(LIBXML_VERSION_EXTRA "")
-set(LIBXML_VERSION_NUMBER ${LIBXML_VERSION})
+math(EXPR LIBXML_VERSION_NUMBER "
+    ${LIBXML_MAJOR_VERSION} * 10000 +
+    ${LIBXML_MINOR_VERSION} * 100 +
+    ${LIBXML_MICRO_VERSION}
+")
 
 set(MODULE_EXTENSION "${CMAKE_SHARED_LIBRARY_SUFFIX}")