Fix build with >=cmake-3.4

Gentoo-bug: 568430

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -59,6 +59,7 @@
 endif(NOT WIN32)
 
 
+include(CheckIncludeFiles)
 check_include_files(stdint.h HAVE_STDINT_H)
 
 configure_file (config-kmplayer.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/config-kmplayer.h )