cmake BUGFIX typo

Refs #114
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c0cd13..8a61f9e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 project(libnetconf2 C)
 include(GNUInstallDirs)
 include(CheckFunctionExists)
-include(CheckIncludeFiles)
+include(CheckIncludeFile)
 
 # include custom Modules
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/CMakeModules/")