cmake: support git info in released tarballs

CMakeLists.txt

@@ -228,17 +228,7 @@ elseif(NOT MSVC)
   set(EXTRA_LIBRARIES ${RT} ${PTHREAD} ${DL})
 endif()
 
-file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/version")
-find_package(Git QUIET)
-if(Git_FOUND OR GIT_FOUND)
-  message(STATUS "Found Git: ${GIT_EXECUTABLE}")
-  add_custom_target(version ALL "${CMAKE_COMMAND}" "-D" "GIT=${GIT_EXECUTABLE}" "-D" "TO=${CMAKE_BINARY_DIR}/version/version.h" "-P" "src/version.cmake" WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}")
-else()
-  message(STATUS "WARNING: Git was not found!")
-  set(VERSIONTAG "unknown")
-  configure_file("src/version.h.in" "version/version.h")
-  add_custom_target(version ALL)
-endif()
+include(version.cmake)
 
 add_subdirectory(src)
 add_subdirectory(tests)