Fix android.gypi to provide correct include and library paths when using standalone Android toolchain.

R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10910062

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12425 ce2b1a6d-e550-0410-aec6-3dcde31c8c00