Teach `validate` script how to `--help`
Teach `validate` script how to `--help`

This basically turns the comment at the beginning of the `validate`
shell script into an interactive `--help` output plus some minor additions.

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