[CMake] Add CppADCG as optional dependency

CMakeLists.txt

@@ -94,6 +94,12 @@ IF(CPPAD_FOUND)
     ADD_DEFINITIONS(-DPINOCCHIO_CPPAD_REQUIRES_MATRIX_BASE_PLUGIN)
     PKG_CONFIG_APPEND_CFLAGS("-DPINOCCHIO_CPPAD_REQUIRES_MATRIX_BASE_PLUGIN")
   ENDIF(NOT ${CPPAD_VERSION} VERSION_GREATER "3.3.0")
+
+  ADD_OPTIONAL_DEPENDENCY("cppadcg")
+  IF(CPPADCG_FOUND)
+    ADD_DEFINITIONS(-DPINOCCHIO_WITH_CPPADCG_SUPPORT)
+    PKG_CONFIG_APPEND_CFLAGS("-DPINOCCHIO_WITH_CPPADCG_SUPPORT")
+  ENDIF(CPPADCG_FOUND)
 ENDIF(CPPAD_FOUND)
 
 # Special care of urdfdom version