Set correct include directory for fftw

dlib/CMakeLists.txt

@@ -367,13 +367,12 @@ if (NOT TARGET dlib)
          # make sure fftw3.h is in the include path
          find_path(fftw_path fftw3.h)
          if (fftw AND fftw_path)
-            get_filename_component(fftw_path2 ${fftw_path} PATH CACHE)
-            include_directories(${fftw_path2})
+            include_directories(${fftw_path})
             set(dlib_needed_libraries ${dlib_needed_libraries} ${fftw} )
          else()
             set(DLIB_LINK_WITH_FFTW OFF CACHE STRING ${DLIB_LINK_WITH_SQLITE3_STR} FORCE )
          endif()
-         mark_as_advanced(fftw fftw_path fftw_path2)
+         mark_as_advanced(fftw fftw_path)
       endif()