[cmake] Add target_include_directories for Boost.

This is missing when compiling with clang on Mac OS Catalina.
Moreover it seems needed anyway.

CMakeLists.txt

@@ -171,6 +171,8 @@ SET(${PROJECT_NAME}_SOURCES
 ADD_LIBRARY(${PROJECT_NAME} SHARED
   ${${PROJECT_NAME}_SOURCES} ${${PROJECT_NAME}_HEADERS})
 TARGET_INCLUDE_DIRECTORIES(${PROJECT_NAME} PUBLIC $<INSTALL_INTERFACE:include>)
+TARGET_INCLUDE_DIRECTORIES(${PROJECT_NAME}
+  SYSTEM PUBLIC ${Boost_INCLUDE_DIRS})
 TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${Boost_LIBRARIES}
   dynamic-graph::dynamic-graph pinocchio::pinocchio)
 

tests/CMakeLists.txt

@@ -106,6 +106,9 @@ IF(UNIX)
   ADD_EXECUTABLE(test_abstract_interface tools/test_abstract_interface.cpp)
   TARGET_LINK_LIBRARIES(test_abstract_interface
     pluginabstract ${CMAKE_DL_LIBS} ${Boost_LIBRARIES})
+  TARGET_INCLUDE_DIRECTORIES(test_abstract_interface
+    SYSTEM PUBLIC ${Boost_INCLUDE_DIRS})
+
 ENDIF(UNIX)
 
 FOREACH(path ${tests})
@@ -116,6 +119,9 @@ FOREACH(path ${tests})
     ${TEST_${test}_LIBS} ${TEST_${test}_EXT_LIBS}
     dynamic-graph::dynamic-graph)
 
+  TARGET_INCLUDE_DIRECTORIES(${test}
+    SYSTEM PUBLIC ${Boost_INCLUDE_DIRS})
+
   IF(UNIX)
     TARGET_LINK_LIBRARIES(${test} ${CMAKE_DL_LIBS})
   ENDIF(UNIX)