minor cgal fix

Former-commit-id: 396fa1555bb0c6fb15a04406f42c4cb2acce70e1

shared/cmake/libigl.cmake

@@ -90,7 +90,7 @@ function(compile_igl_module module_dir prefix)
   else()
     add_library(igl_${module_name} INTERFACE)
   endif()
-  
+
   target_link_libraries(igl_${module_name} ${IGL_SCOPE} igl_common)
   if(NOT module_name STREQUAL "core")
 	  target_link_libraries(igl_${module_name} ${IGL_SCOPE} igl_core)
@@ -132,6 +132,7 @@ if(LIBIGL_WITH_CGAL)
   if(CGAL_FOUND)
     compile_igl_module("cgal" "copyleft/")
     find_package(Boost 1.48 REQUIRED thread system)
+    target_include_directories(igl_cgal ${IGL_SCOPE} ${CGAL_INCLUDE_DIRS})
     target_link_libraries(igl_cgal ${IGL_SCOPE} CGAL::CGAL CGAL::CGAL_Core ${Boost_LIBRARIES})
   else()
     set(LIBIGL_WITH_CGAL OFF CACHE BOOL "" FORCE)
@@ -359,4 +360,3 @@ if(LIBIGL_WITH_XML)
   compile_igl_module("xml" "")
   target_link_libraries(igl_xml ${IGL_SCOPE} tinyxml2)
 endif()
-