title: cmake include_directories order AFTER/BEFORE
body: <p>I have a file in source tree which name is "time.h", exactly as system "time.h". This cannot be changed. I have encountered a problem with cmake that when I use include_library option it is translated to -I flag which means that my custom "time.h" takes prcedence over system time.h even for &lt;> includes. This is a definiti no-no.</p>
  
  <p>I tried using include_directories (AFTER dir1 dir2) but it still generate -I option instead of expected -idirafter.</p>