removed own boost::headers

Author: basisunus

Superbuild/BoostConfig.cmake.in

@@ -121,13 +121,5 @@ if(@BUILD_WITH_PYTHON@)
   _scirun_define_boost_target(python@SCI_PYTHON_VERSION_SHORT_WIN32@)
 endif()
 
-# ---------------------------------------------------------------------------
-# Headers target
-# ---------------------------------------------------------------------------
-add_library(Boost::headers INTERFACE IMPORTED)
-set_target_properties(Boost::headers PROPERTIES
-  INTERFACE_INCLUDE_DIRECTORIES "${Boost_INCLUDE_DIRS}"
-)
-
 # Legacy variable — intentionally empty
 set(Boost_LIBRARIES "")