Change how core foundation headers are copied to ensure it *always* runs
Change how core foundation headers are copied to ensure it *always* runs

Description:

The weirdness was that BeforeTargets=”Build” didn’t always run because apparently
“Build” is a special virtual target that doesn’t always run. (no clue why it didn’t on auto layout).
The fix is to change it so that it runs as part of generate sources which should always run, I think?

How Verified: auto layout builds now

Reviewed-by: pradipd, artems

vkvenkat/WinObjC,Microsoft/WinObjC,ehren/WinObjC,ehren/WinObjC,autodesk-forks/WinObjC,bSr43/WinObjC,bSr43/WinObjC,rajsesh-msft/WinObjC,pradipd/WinObjC,nathpete-msft/WinObjC,pradipd/WinObjC,nathpete-msft/WinObjC,nathpete-msft/WinObjC,MSFTFox/WinObjC,pradipd/WinObjC,ehren/WinObjC,bbowman/WinObjC,vkvenkat/WinObjC,afaruqui/WinObjC,rajsesh-msft/WinObjC,vkvenkat/WinObjC,yweijiang/WinObjC,autodesk-forks/WinObjC,bbowman/WinObjC,nathpete-msft/WinObjC,autodesk-forks/WinObjC,ehren/WinObjC,Microsoft/WinObjC,yweijiang/WinObjC,rajsesh-msft/WinObjC,vkvenkat/WinObjC,yweijiang/WinObjC,bbowman/WinObjC,pradipd/WinObjC,afaruqui/WinObjC,autodesk-forks/WinObjC,afaruqui/WinObjC,afaruqui/WinObjC,bSr43/WinObjC,ehren/WinObjC,bSr43/WinObjC,bbowman/WinObjC,MSFTFox/WinObjC,Microsoft/WinObjC,MSFTFox/WinObjC,nathpete-msft/WinObjC,yweijiang/WinObjC,pradipd/WinObjC,Microsoft/WinObjC,bbowman/WinObjC,rajsesh-msft/WinObjC,MSFTFox/WinObjC