Fix overflow testing in sbrk. am: 1944780b am: 3a5ebf31 -s ours am: d95336ac am: 09933196 am: 0ae30d9a am: 83b0671a * commit '83b0671a': Fix overflow testing in sbrk. Change-Id: Id325431f9de4bdfe102381da21445fa0781ccc82