Use "--whitespace nowarn" in `arc patch` to respect trailing whitespace
Use "--whitespace nowarn" in `arc patch` to respect trailing whitespace

Summary: Fixes T10008. Git tries to fix some issues by default (apparently? empirically; not consistent with documentation, I think?), but patches from `arc patch` are "always" accurate (disregarding other bugs we might have -- basically, they haven't been emailed or copy/pasted or anything like that) so we can just tell it to apply the patch exactly as-is.

Test Plan: {F1029182}

Reviewers: chad, joshuaspence

Reviewed By: chad, joshuaspence

Maniphest Tasks: T10008

Differential Revision: https://secure.phabricator.com/D14816

coursera/arcanist,haskell-infra/arcanist,Khan/arcanist,calblueprint/arcanist,Khan/arcanist,zhihu/arcanist,phacility/arcanist,wikimedia/phabricator-arcanist,codelabs-ch/arcanist,wikimedia/phabricator-arcanist,folsom-labs/arcanist,memsql/arcanist,jra3/arcanist,chundongwang/arcanist,codelabs-ch/arcanist,uber/arcanist,haskell-infra/arcanist,calblueprint/arcanist,haskell-infra/arcanist,aik099/arcanist,phacility/arcanist,aik099/arcanist,codelabs-ch/arcanist,memsql/arcanist,coursera/arcanist,memsql/arcanist,phacility/arcanist,chundongwang/arcanist,fivestars/arcanist,Khan/arcanist,folsom-labs/arcanist,jra3/arcanist,haskell-infra/arcanist,phacility/arcanist,r4nt/arcanist,jra3/arcanist,aik099/arcanist,fivestars/arcanist,chundongwang/arcanist,fivestars/arcanist,r4nt/arcanist,calblueprint/arcanist,Khan/arcanist,r4nt/arcanist,folsom-labs/arcanist,jra3/arcanist,calblueprint/arcanist,codelabs-ch/arcanist,fivestars/arcanist,uber/arcanist,phacility/arcanist,wikimedia/phabricator-arcanist,uber/arcanist,r4nt/arcanist,wikimedia/phabricator-arcanist,chundongwang/arcanist,coursera/arcanist,zhihu/arcanist,uber/arcanist,zhihu/arcanist,coursera/arcanist,codelabs-ch/arcanist,zhihu/arcanist,aik099/arcanist,folsom-labs/arcanist,memsql/arcanist