Added meshoptimizer library

modules/world/SCsub

@@ -7,12 +7,15 @@ env_world = env_modules.Clone()
 files = [
 	"*.cpp",
 	"mesher/*.cpp",
+	"thirdparty/meshoptimizer/*.cpp",
 	"thirdparty/RVO2-3D/*.cpp"
 ]
 
 for f in files:
 	env_world.add_source_files(env.modules_sources, f)
 
+env_world.Append(CPPDEFINES=["MESHOPTIMIZER_ZYLANN_NEVER_COLLAPSE_BORDERS"])
+
 # Ignored clang warnings because Godot's codebase is old and isn't using override yet
 if env['platform'] == 'osx' or env['platform'] == 'android':
     env_world.Append(CXXFLAGS=['-Wno-inconsistent-missing-override'])