Summary: The function wrapper for LDBCommand::SelectCommand is too long so that Windows build fails with warning "decorated name length exceeded, name was truncated". Shrink the length by using a struct.
Test Plan: Build on both of Linux and Windows and make sure the warning doesn't show in either platform.
Reviewers: andrewkr, adsharma, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D58965