[hack] Revert ocamlbuild hacks for 3.12
[hack] Revert ocamlbuild hacks for 3.12

Summary: Reverts {D1692564}

Reviewed By: @jwatzman

Differential Revision: D2151433

lyip1992/flow,AprilArcus/flow,ForbesLindesay/flow,jeffmo/flow,davidmason/flow,danvk/flow,mroch/flow,Drooids/flow,nmote/flow,Eyyub/flow,davidmason/flow,KevinTCoughlin/flow,claudiopro/flow,chenglou/flow,shiftcars/flow,JonathanUsername/flow,d14b3l/flow,Drooids/flow,ForbesLindesay/flow,cesarandreu/flow,shiftcars/flow,mcanthony/flow-type,danvk/flow,ForbesLindesay/flow,popham/flow,mroch/flow,fletcherw/flow,Fresheyeball/flow,gabelevi/flow,TiddoLangerak/flow,davidmason/flow,d14b3l/flow,popham/flow,JeckoHeroOrg/flow,OCamlPro/flow,matklad/flow,davidmason/flow,jgrund/flow,jeffutter/flow,jeffmo/flow,chenglou/flow,jdelStrother/flow,MichaelDeBoey/flow,TiddoLangerak/flow,Eyyub/flow,KevinTCoughlin/flow,graue/flow,Fresheyeball/flow,samwgoldman/flow,TiddoLangerak/flow,fletcherw/flow,fletcherw/flow,AgentME/flow,jamesgpearce/flow,gabro/flow,d14b3l/flow,mcanthony/flow-type,YelaSeamless/flow,jeffmo/flow,jeffmo/flow,gabelevi/flow,jdelStrother/flow,CJstar/flow,facebook/flow,davidmason/flow,dv/flow,Wanderfalke/flow,jgrund/flow,jeffmo/flow,claudiopro/flow,ylu1317/flow,CJstar/flow,darioajr/flow,jdelStrother/flow,popham/flow,jdelStrother/flow,JonathanUsername/flow,Eyyub/flow,jeffmo/flow,d14b3l/flow,KevinTCoughlin/flow,jdelStrother/flow,mroch/flow,OCamlPro/flow,chenglou/flow,matklad/flow,claudiopro/flow,gabelevi/flow,Wanderfalke/flow,chenglou/flow,ianobermiller/flow,Jericho25/flow,KevinTCoughlin/flow,paulshen/flow,matklad/flow,YelaSeamless/flow,ylu1317/flow,AgentME/flow,ianobermiller/flow,samwgoldman/flow,OCamlPro/flow,jgrund/flow,Jericho25/flow,MichaelDeBoey/flow,JohnyDays/flow,AprilArcus/flow,facebook/flow,gabro/flow,lyip1992/flow,jgrund/flow,facebook/flow,matklad/flow,mroch/flow,JonathanUsername/flow,jamesgpearce/flow,Wanderfalke/flow,graue/flow,popham/flow,Fresheyeball/flow,ylu1317/flow,JeckoHeroOrg/flow,d14b3l/flow,graue/flow,gabro/flow,jdelStrother/flow,JeckoHeroOrg/flow,rafaelstz/flow,asivitz/flow,dv/flow,JonathanUsername/flow,shiftcars/flow,paulshen/flow,facebook/flow,JonathanUsername/flow,ForbesLindesay/flow,jamesgpearce/flow,rafaelstz/flow,mroch/flow,samwgoldman/flow,AgentME/flow,danvk/flow,Wanderfalke/flow,JohnyDays/flow,AprilArcus/flow,darioajr/flow,nmote/flow,MichaelDeBoey/flow,ianobermiller/flow,cesarandreu/flow,nmote/flow,ylu1317/flow,shiftcars/flow,YelaSeamless/flow,claudiopro/flow,facebook/flow,paulshen/flow,mcanthony/flow-type,siddhartharay007/flow,graue/flow,Jericho25/flow,lyip1992/flow,siddhartharay007/flow,YelaSeamless/flow,JohnyDays/flow,fletcherw/flow,asivitz/flow,TiddoLangerak/flow,Drooids/flow,gabelevi/flow,jamesgpearce/flow,chenglou/flow,popham/flow,nmote/flow,Eyyub/flow,gabelevi/flow,popham/flow,Fresheyeball/flow,ForbesLindesay/flow,rafaelstz/flow,jgrund/flow,claudiopro/flow,CJstar/flow,darioajr/flow,siddhartharay007/flow,cesarandreu/flow,gabro/flow,dv/flow,MichaelDeBoey/flow,paulshen/flow,fletcherw/flow,Drooids/flow,ianobermiller/flow,jeffutter/flow,d14b3l/flow,samwgoldman/flow,chenglou/flow,ylu1317/flow,rafaelstz/flow,lyip1992/flow,asivitz/flow,JeckoHeroOrg/flow,asivitz/flow,danvk/flow,nmote/flow,samwgoldman/flow,AprilArcus/flow,MichaelDeBoey/flow,samwgoldman/flow,jeffutter/flow,dv/flow,gabelevi/flow,ForbesLindesay/flow,samwgoldman/flow,JohnyDays/flow,gabelevi/flow,rafaelstz/flow,graue/flow,JonathanUsername/flow,mcanthony/flow-type,AgentME/flow,jamesgpearce/flow,mroch/flow,jamesgpearce/flow,JeckoHeroOrg/flow,popham/flow,jamesgpearce/flow,facebook/flow,nmote/flow,siddhartharay007/flow,AprilArcus/flow,darioajr/flow,OCamlPro/flow,AgentME/flow,matklad/flow,TiddoLangerak/flow,YelaSeamless/flow,shiftcars/flow,nmote/flow,fletcherw/flow,graue/flow,AprilArcus/flow,mroch/flow,JonathanUsername/flow,gabro/flow,shiftcars/flow,cesarandreu/flow,jeffutter/flow,gabro/flow,jgrund/flow,facebook/flow,CJstar/flow