IRGen: tweak spacing in comment (NFC)
IRGen: tweak spacing in comment (NFC)

Comments are not rendered as justified by spacing. This corrects the
spacing of the comment to match the style of the codebase.

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