Fix overflow testing in sbrk. am: 1944780b am: 3a5ebf31 -s ours am: d95336ac am: 09933196 am: 0ae30d9a am: 83b0671a am: 10a48fb5 am: fd84d78b am: b4d92e13 * commit 'b4d92e13': Fix overflow testing in sbrk. Change-Id: I0e8c70deedb9f43204d306a5fdad22b14703dbe5