GSB: Perform conditional requirement inference in AbstractGenericSignatureRequest too
GSB: Perform conditional requirement inference in AbstractGenericSignatureRequest too

There's no way to trigger this from a test right now; it's
for some changes @jckarter is working on.

roambotics/swift,atrick/swift,rudkx/swift,roambotics/swift,glessard/swift,JGiola/swift,ahoppen/swift,glessard/swift,apple/swift,roambotics/swift,gregomni/swift,ahoppen/swift,rudkx/swift,JGiola/swift,JGiola/swift,ahoppen/swift,benlangmuir/swift,gregomni/swift,JGiola/swift,apple/swift,roambotics/swift,gregomni/swift,JGiola/swift,ahoppen/swift,apple/swift,gregomni/swift,apple/swift,atrick/swift,rudkx/swift,benlangmuir/swift,glessard/swift,JGiola/swift,gregomni/swift,roambotics/swift,apple/swift,atrick/swift,rudkx/swift,glessard/swift,ahoppen/swift,atrick/swift,rudkx/swift,atrick/swift,gregomni/swift,roambotics/swift,glessard/swift,glessard/swift,benlangmuir/swift,benlangmuir/swift,benlangmuir/swift,benlangmuir/swift,ahoppen/swift,atrick/swift,apple/swift,rudkx/swift