Removed ironpython-2.7.7-rc2 definition

plugins/python-build/share/python-build/ironpython-2.7.7-rc2

@@ -1,2 +0,0 @@
-install_package "IronPython-2.7.7rc2" "https://github.com/IronLanguages/main/releases/download/ipy-2.7.7-rc2/IronPython-2.7.7rc2-unix.tar.bz2#338b855d007a2f8f12498fe67039483e671c98f6ea8320add4cdedd53b118113" ironpython
-# FIXME: have not confirmed to install setuptools into IronPython yet