Tidy up cmake include order in aom_configure.cmake.

Change-Id: I7dae1b184fe174bad782f34a6b213de0286e90f4

build/cmake/aom_configure.cmake

@@ -10,6 +10,9 @@
 ##
 cmake_minimum_required(VERSION 3.2)
 
+include(FindGit)
+include(FindPerl)
+
 include("${AOM_ROOT}/build/cmake/aom_config_defaults.cmake")
 include("${AOM_ROOT}/build/cmake/compiler_flags.cmake")
 include("${AOM_ROOT}/build/cmake/compiler_tests.cmake")
@@ -68,9 +71,6 @@ endif ()
 
 include("${AOM_ROOT}/build/cmake/targets/${AOM_TARGET_CPU}.cmake")
 
-include(FindGit)
-include(FindPerl)
-
 # Test compiler flags.
 if (MSVC)
   add_compiler_flag_if_supported("/W3")