Specify CMake module dir before trying to find Corrade.

We need file from that module dir to find it.

CMakeLists.txt

@@ -27,6 +27,7 @@ cmake_minimum_required(VERSION 2.8.8)
 project(Magnum)
 
 # Find Corrade first so we can check on the target
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/modules/")
 find_package(Corrade REQUIRED)
 
 include(CMakeDependentOption)
@@ -66,8 +67,6 @@ if(BUILD_TESTS)
     enable_testing()
 endif()
 
-set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/modules/")
-
 # If targeting NaCl or Emscripten, set explicit OpenGL ES 2.0 support
 if(CORRADE_TARGET_NACL OR CORRADE_TARGET_EMSCRIPTEN)
     set(TARGET_GLES 1)