[Basic] Don't use defined(LLVM_ENABLE_STATS) as it can be set to 0
[Basic] Don't use defined(LLVM_ENABLE_STATS) as it can be set to 0

LLVM_ENABLE_STATS can be defined to 0 since
https://reviews.llvm.org/D91094.

rdar://73834542

rudkx/swift,hooman/swift,rudkx/swift,apple/swift,xwu/swift,atrick/swift,glessard/swift,apple/swift,xwu/swift,ahoppen/swift,xwu/swift,glessard/swift,atrick/swift,roambotics/swift,parkera/swift,ahoppen/swift,tkremenek/swift,atrick/swift,roambotics/swift,parkera/swift,glessard/swift,gregomni/swift,benlangmuir/swift,JGiola/swift,parkera/swift,benlangmuir/swift,glessard/swift,hooman/swift,glessard/swift,parkera/swift,hooman/swift,gregomni/swift,atrick/swift,roambotics/swift,JGiola/swift,xwu/swift,tkremenek/swift,JGiola/swift,atrick/swift,rudkx/swift,roambotics/swift,ahoppen/swift,apple/swift,gregomni/swift,roambotics/swift,xwu/swift,parkera/swift,gregomni/swift,parkera/swift,tkremenek/swift,apple/swift,benlangmuir/swift,ahoppen/swift,JGiola/swift,benlangmuir/swift,tkremenek/swift,tkremenek/swift,roambotics/swift,parkera/swift,apple/swift,ahoppen/swift,gregomni/swift,tkremenek/swift,JGiola/swift,apple/swift,benlangmuir/swift,rudkx/swift,tkremenek/swift,atrick/swift,xwu/swift,ahoppen/swift,JGiola/swift,rudkx/swift,hooman/swift,glessard/swift,benlangmuir/swift,hooman/swift,rudkx/swift,parkera/swift,gregomni/swift,hooman/swift,hooman/swift,xwu/swift