Remove bld.bat (#3140)

Summary:
This was already deleted in #2671 but for some reason didn't get picked in the merge

Pull Request resolved: #3140

Reviewed By: datumbox

Differential Revision: D25395647

Pulled By: fmassa

fbshipit-source-id: c8eb3692266deaccf5f00b314e84ec102bea60cb

Author: fmassa