Remove unneeded parts of build script
Remove unneeded parts of build script

Summary: Remove an unneeded autoconf flag, as it causes the build to fail on missing boost-context

Reviewed By: yfeldblum

Differential Revision: D5815646

fbshipit-source-id: cb6544593de9fbf8248506b09c56412b4635b30c

rklabs/folly,Orvid/folly,facebook/folly,facebook/folly,facebook/folly,rklabs/folly,facebook/folly,Orvid/folly,Orvid/folly,Orvid/folly,Orvid/folly,rklabs/folly,rklabs/folly,rklabs/folly,facebook/folly