Move enable language in cmakelist.txt to avoid configure warning (#439)

Author: mcbarton

CMakeLists.txt

@@ -1,10 +1,5 @@
 cmake_minimum_required(VERSION 3.13)
 
-enable_language(CXX)
-set(CMAKE_CXX_EXTENSIONS NO)
-
-include(GNUInstallDirs)
-
 set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH}
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
@@ -59,6 +54,9 @@ if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
     endif()
   endif()
 
+enable_language(CXX)
+set(CMAKE_CXX_EXTENSIONS NO)
+include(GNUInstallDirs)
   option(USE_CLING "Use Cling as backend" OFF)
   option(USE_REPL "Use clang-repl as backend" ON)