Fix generate of XML documentation.

CMakeLists.txt

@@ -148,6 +148,7 @@ SET(${PROJECT_NAME}_HEADERS
   include/hpp/fcl/internal/traversal.h
   )
 
+add_subdirectory(doc)
 add_subdirectory(src)
 if (BUILD_PYTHON_INTERFACE)
   add_subdirectory(python)

doc/CMakeLists.txt

+SET(DOXYGEN_XML_OUTPUT          "doxygen-xml"      PARENT_SCOPE)
+SET(DOXYGEN_FILE_PATTERNS       "*.h  *.hh  *.hxx" PARENT_SCOPE)
+SET(DOXYGEN_GENERATE_XML        "YES"              PARENT_SCOPE)
+SET(DOXYGEN_EXPAND_ONLY_PREDEF  "NO"               PARENT_SCOPE)

doc/Doxyfile.extra.in

-FILE_PATTERNS          = *.h  *.hh  *.hxx
-GENERATE_XML           = YES
-EXPAND_ONLY_PREDEF     = NO