remove submodule

.gitmodules

@@ -10,7 +10,3 @@
 [submodule "tests/cpp-tests/Resources/ccs-res"]
         path = tests/cpp-tests/Resources/ccs-res
         url = git://github.com/dumganhar/ccs-res.git
-[submodule "external"]
-	path = external
-	url = git://github.com/cocos2d/cocos2d-x-3rd-party-libs-bin.git
-	branch = v3