Improve the warning about -fllvm and -fPIC/-dynamic conflicting
Improve the warning about -fllvm and -fPIC/-dynamic conflicting

We now do it while parsing the flags, rather than at the end.
It also now uses the Platform's arch/os variables, rather than Config's.

gridaphobe/ghc,GaloisInc/halvm-ghc,fmthoma/ghc,mcmaniac/ghc,shlevy/ghc,nomeata/ghc,wxwxwwxxx/ghc,lukexi/ghc,snoyberg/ghc,mfine/ghc,mcmaniac/ghc,gcampax/ghc,vikraman/ghc,mettekou/ghc,da-x/ghc,hferreiro/replay,mfine/ghc,siddhanathan/ghc,ml9951/ghc,ml9951/ghc,oldmanmike/ghc,ghc-android/ghc,hferreiro/replay,hferreiro/replay,wxwxwwxxx/ghc,lukexi/ghc-7.8-arm64,christiaanb/ghc,elieux/ghc,ghc-android/ghc,gcampax/ghc,anton-dessiatov/ghc,vikraman/ghc,siddhanathan/ghc,holzensp/ghc,TomMD/ghc,TomMD/ghc,ekmett/ghc,ezyang/ghc,nkaretnikov/ghc,nushio3/ghc,TomMD/ghc,shlevy/ghc,snoyberg/ghc,ilyasergey/GHC-XAppFix,ml9951/ghc,ml9951/ghc,sgillespie/ghc,lukexi/ghc,christiaanb/ghc,green-haskell/ghc,christiaanb/ghc,sgillespie/ghc,mcmaniac/ghc,ezyang/ghc,olsner/ghc,anton-dessiatov/ghc,mfine/ghc,lukexi/ghc-7.8-arm64,mettekou/ghc,acowley/ghc,GaloisInc/halvm-ghc,mettekou/ghc,hferreiro/replay,tibbe/ghc,da-x/ghc,fmthoma/ghc,urbanslug/ghc,nathyong/microghc-ghc,da-x/ghc,bitemyapp/ghc,anton-dessiatov/ghc,urbanslug/ghc,AlexanderPankiv/ghc,acowley/ghc,jstolarek/ghc,mfine/ghc,oldmanmike/ghc,ezyang/ghc,spacekitteh/smcghc,sgillespie/ghc,nomeata/ghc,lukexi/ghc,GaloisInc/halvm-ghc,anton-dessiatov/ghc,AlexanderPankiv/ghc,tjakway/ghcjvm,forked-upstream-packages-for-ghcjs/ghc,vTurbine/ghc,christiaanb/ghc,shlevy/ghc,forked-upstream-packages-for-ghcjs/ghc,shlevy/ghc,AlexanderPankiv/ghc,ezyang/ghc,siddhanathan/ghc,olsner/ghc,ezyang/ghc,tibbe/ghc,fmthoma/ghc,frantisekfarka/ghc-dsi,nushio3/ghc,holzensp/ghc,vikraman/ghc,mcschroeder/ghc,nkaretnikov/ghc,mcschroeder/ghc,forked-upstream-packages-for-ghcjs/ghc,olsner/ghc,elieux/ghc,nathyong/microghc-ghc,GaloisInc/halvm-ghc,ilyasergey/GHC-XAppFix,christiaanb/ghc,siddhanathan/ghc,TomMD/ghc,sdiehl/ghc,shlevy/ghc,nkaretnikov/ghc,acowley/ghc,olsner/ghc,sgillespie/ghc,sdiehl/ghc,frantisekfarka/ghc-dsi,gcampax/ghc,jstolarek/ghc,ghc-android/ghc,holzensp/ghc,ghc-android/ghc,ilyasergey/GHC-XAppFix,nathyong/microghc-ghc,olsner/ghc,nushio3/ghc,frantisekfarka/ghc-dsi,da-x/ghc,ezyang/ghc,nkaretnikov/ghc,oldmanmike/ghc,urbanslug/ghc,bitemyapp/ghc,spacekitteh/smcghc,ekmett/ghc,tibbe/ghc,shlevy/ghc,gcampax/ghc,ghc-android/ghc,christiaanb/ghc,spacekitteh/smcghc,mfine/ghc,gcampax/ghc,wxwxwwxxx/ghc,olsner/ghc,da-x/ghc,nushio3/ghc,lukexi/ghc,anton-dessiatov/ghc,tjakway/ghcjvm,ekmett/ghc,olsner/ghc,tibbe/ghc,wxwxwwxxx/ghc,ekmett/ghc,wxwxwwxxx/ghc,ryantm/ghc,nathyong/microghc-ghc,gridaphobe/ghc,nathyong/microghc-ghc,mcschroeder/ghc,ghc-android/ghc,sdiehl/ghc,sgillespie/ghc,christiaanb/ghc,ryantm/ghc,holzensp/ghc,oldmanmike/ghc,gcampax/ghc,sdiehl/ghc,urbanslug/ghc,jstolarek/ghc,gridaphobe/ghc,snoyberg/ghc,AlexanderPankiv/ghc,tjakway/ghcjvm,elieux/ghc,jstolarek/ghc,frantisekfarka/ghc-dsi,sdiehl/ghc,ryantm/ghc,bitemyapp/ghc,mcschroeder/ghc,TomMD/ghc,green-haskell/ghc,mettekou/ghc,nkaretnikov/ghc,da-x/ghc,GaloisInc/halvm-ghc,tjakway/ghcjvm,vTurbine/ghc,ml9951/ghc,shlevy/ghc,nomeata/ghc,AlexanderPankiv/ghc,gridaphobe/ghc,oldmanmike/ghc,nushio3/ghc,vikraman/ghc,green-haskell/ghc,mcschroeder/ghc,TomMD/ghc,tjakway/ghcjvm,gcampax/ghc,da-x/ghc,tibbe/ghc,spacekitteh/smcghc,lukexi/ghc,siddhanathan/ghc,oldmanmike/ghc,nomeata/ghc,elieux/ghc,TomMD/ghc,ilyasergey/GHC-XAppFix,fmthoma/ghc,sgillespie/ghc,lukexi/ghc-7.8-arm64,vikraman/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,ghc-android/ghc,nushio3/ghc,siddhanathan/ghc,acowley/ghc,vTurbine/ghc,nathyong/microghc-ghc,ryantm/ghc,sdiehl/ghc,mcmaniac/ghc,nkaretnikov/ghc,mfine/ghc,vTurbine/ghc,urbanslug/ghc,mettekou/ghc,mfine/ghc,bitemyapp/ghc,vTurbine/ghc,tjakway/ghcjvm,sdiehl/ghc,hferreiro/replay,vTurbine/ghc,gridaphobe/ghc,lukexi/ghc-7.8-arm64,frantisekfarka/ghc-dsi,spacekitteh/smcghc,mcschroeder/ghc,elieux/ghc,GaloisInc/halvm-ghc,mettekou/ghc,forked-upstream-packages-for-ghcjs/ghc,siddhanathan/ghc,nomeata/ghc,AlexanderPankiv/ghc,nathyong/microghc-ghc,anton-dessiatov/ghc,tjakway/ghcjvm,elieux/ghc,ml9951/ghc,bitemyapp/ghc,acowley/ghc,acowley/ghc,snoyberg/ghc,forked-upstream-packages-for-ghcjs/ghc,vikraman/ghc,ekmett/ghc,mettekou/ghc,green-haskell/ghc,GaloisInc/halvm-ghc,hferreiro/replay,snoyberg/ghc,ml9951/ghc,mcschroeder/ghc,urbanslug/ghc,oldmanmike/ghc,gridaphobe/ghc,mcmaniac/ghc,anton-dessiatov/ghc,AlexanderPankiv/ghc,sgillespie/ghc,snoyberg/ghc,hferreiro/replay,nkaretnikov/ghc,jstolarek/ghc,elieux/ghc,fmthoma/ghc,wxwxwwxxx/ghc,fmthoma/ghc,lukexi/ghc-7.8-arm64,gridaphobe/ghc,ezyang/ghc,snoyberg/ghc,nushio3/ghc,vikraman/ghc,green-haskell/ghc,wxwxwwxxx/ghc,acowley/ghc,holzensp/ghc,fmthoma/ghc,ml9951/ghc,vTurbine/ghc,urbanslug/ghc,ryantm/ghc