Add Zero Heurestics to BranchProbabilityInfo. If we compare value to zero we decide whether condition is likely to be true this way:
Add Zero Heurestics to BranchProbabilityInfo. If we compare value to zero we
decide whether condition is likely to be true this way:

x == 0  ->  false
x <  0  ->  false
x <= 0  ->  false
x != 0  ->  true
x >  0  ->  true
x >= 0  ->  true


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@136583 91177308-0d34-0410-b5e6-96231b3b80d8

chubbymaggie/asap,llvm-mirror/llvm,dslab-epfl/asap,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,chubbymaggie/asap,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,dslab-epfl/asap,apple/swift-llvm,GPUOpen-Drivers/llvm,dslab-epfl/asap,llvm-mirror/llvm,chubbymaggie/asap,chubbymaggie/asap,apple/swift-llvm,dslab-epfl/asap,llvm-mirror/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,dslab-epfl/asap,chubbymaggie/asap,llvm-mirror/llvm,chubbymaggie/asap,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm