Make this code more robust by not thinking we are making progress if zero bytes were read.
Make this code more robust by not thinking we are making progress
if zero bytes were read.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@85922 91177308-0d34-0410-b5e6-96231b3b80d8

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