Simulate: Use new cmake system fix build errors introduced with rebase

CMakeLists.txt

@@ -39,6 +39,7 @@ enable_language(CXX)
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
 option(MUJOCO_BUILD_EXAMPLES "Build samples for MuJoCo" ON)
+option(MUJOCO_BUILD_SIMULATE "Build simulate library for MuJoCo" ON)
 option(MUJOCO_BUILD_TESTS "Build tests for MuJoCo" ON)
 option(MUJOCO_TEST_PYTHON_UTIL "Build and test utility libraries for Python bindings" ON)
 
@@ -47,6 +48,11 @@ if(APPLE AND MUJOCO_BUILD_EXAMPLES)
   enable_language(OBJCXX)
 endif()
 
+if(APPLE AND MUJOCO_BUILD_SIMULATE)
+  enable_language(OBJC)
+  enable_language(OBJCXX)
+endif()
+
 include(MujocoOptions)
 include(MujocoMacOS)
 include(MujocoDependencies)
@@ -156,6 +162,10 @@ if(MUJOCO_BUILD_EXAMPLES)
   add_subdirectory(sample)
 endif()
 
+if(MUJOCO_BUILD_SIMULATE)
+  add_subdirectory(simulate)
+endif()
+
 if(BUILD_TESTING AND MUJOCO_BUILD_TESTS)
   enable_testing()
   add_subdirectory(test)