Use version in configure.ac for CMake

Now CMake script reads version from configure.ac to prevent unsynchronized versions

CMakeLists.txt

 cmake_minimum_required(VERSION 3.15)
 
-project(libxml2 VERSION 2.9.12 LANGUAGES C)
+file(STRINGS "configure.ac" CONFIGURE_AC_LINES)
+foreach(line ${CONFIGURE_AC_LINES})
+	if(line MATCHES [[^m4_define\(\[(MAJOR_VERSION|MINOR_VERSION|MICRO_VERSION)\],[ \t]*([0-9]+)\)$]])
+		set(LIBXML_${CMAKE_MATCH_1} ${CMAKE_MATCH_2})
+	elseif(line MATCHES "^(LIBXML_MAJOR_VERSION|LIBXML_MINOR_VERSION|LIBXML_MICRO_VERSION)=([0-9]+)$")
+		set(${CMAKE_MATCH_1} ${CMAKE_MATCH_2})
+	endif()
+endforeach()
+set(VERSION "${LIBXML_MAJOR_VERSION}.${LIBXML_MINOR_VERSION}.${LIBXML_MICRO_VERSION}")
+
+project(libxml2 VERSION ${VERSION} LANGUAGES C)
 
 include(CheckCSourceCompiles)
 include(CheckFunctionExists)
@@ -95,11 +105,6 @@
 	endif()
 endforeach()
 
-set(LIBXML_MAJOR_VERSION ${PROJECT_VERSION_MAJOR})
-set(LIBXML_MINOR_VERSION ${PROJECT_VERSION_MINOR})
-set(LIBXML_MICRO_VERSION ${PROJECT_VERSION_PATCH})
-
-set(VERSION "${LIBXML_MAJOR_VERSION}.${LIBXML_MINOR_VERSION}.${LIBXML_MICRO_VERSION}")
 set(LIBXML_VERSION ${LIBXML_MAJOR_VERSION}0${LIBXML_MINOR_VERSION}0${LIBXML_MICRO_VERSION})
 set(LIBXML_VERSION_STRING "${LIBXML_VERSION}")
 set(LIBXML_VERSION_EXTRA "")