made the blocking component optionnal again

Author: nicolaslg

CMakeLists.txt

@@ -421,8 +421,10 @@ set(LIB_GMDS_CAD GMDSCad)
 add_subdirectory(core/cad)
 set(LIB_GMDS_CADFAC GMDSCadFac)
 add_subdirectory(core/cadfac)
-set(LIB_GMDS_BLOCKING GMDSBlocking)
-add_subdirectory(core/blocking)
+if (ENABLE_BLOCKING)
+    set(LIB_GMDS_BLOCKING GMDSBlocking)
+    add_subdirectory(core/blocking)
+endif ()
 set(LIB_GMDS_SMOOTHY GMDSSmoothy)
 add_subdirectory(core/smoothy)