[ios-sdk] Configure framework to build for armv6 as well as armv7
[ios-sdk] Configure framework to build for armv6 as well as armv7

Summary:
Framework was not configured to build for armv6, so older iPhones/iPads could
not run binaries built with it.

Test Plan:
- Tried building Scrumptious for armv6, which failed before. Works now.

Revert Plan:

Reviewers: jacl, mmarucheck, gregschechte, ayden

Reviewed By: mmarucheck

CC: yariv

Differential Revision: https://phabricator.fb.com/D492800

Subsplash/facebook-ios-sdk,wooga/facebook-ios-sdk,tipbit/facebook-ios-sdk,1234-/facebook-ios-sdk,shepting/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,beamly/facebook-ios-sdk,anthonylai/facebook-ios-sdk,hibu/facebook-ios-sdk,anthonylai/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,TimeIncOSS/facebook-ios-sdk,1234-/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,shepting/facebook-ios-sdk,hibu/facebook-ios-sdk,FiftyThree/facebook-ios-sdk,taptaptap/facebook-ios-sdk,1234-/facebook-ios-sdk,wooga/facebook-ios-sdk,FiftyThree/facebook-ios-sdk,wooga/facebook-ios-sdk,taptaptap/facebook-ios-sdk,Amnysia/facebook-ios-sdk,ShareKit/facebook-ios-sdk,hibu/facebook-ios-sdk,Citrrus/facebook-ios-sdk,TimeIncOSS/facebook-ios-sdk,shepting/facebook-ios-sdk,flovilmart/facebook-ios-sdk,flovilmart/facebook-ios-sdk,ShareKit/facebook-ios-sdk,taptaptap/facebook-ios-sdk,flovilmart/facebook-ios-sdk,shepting/facebook-ios-sdk,flovilmart/facebook-ios-sdk,tipbit/facebook-ios-sdk,Citrrus/facebook-ios-sdk,beamly/facebook-ios-sdk,Citrrus/facebook-ios-sdk,Subsplash/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,hibu/facebook-ios-sdk,flovilmart/facebook-ios-sdk,Subsplash/facebook-ios-sdk,tipbit/facebook-ios-sdk,beamly/facebook-ios-sdk,1234-/facebook-ios-sdk,Amnysia/facebook-ios-sdk,Amnysia/facebook-ios-sdk,ShareKit/facebook-ios-sdk,anthonylai/facebook-ios-sdk,TimeIncOSS/facebook-ios-sdk,1234-/facebook-ios-sdk,hibu/facebook-ios-sdk,shepting/facebook-ios-sdk,FiftyThree/facebook-ios-sdk