Fix overflow testing in sbrk. am: 1944780b62 am: 3a5ebf3154  -s ours am: d95336ac42 am: 0993319651 am: 0ae30d9af8 am: 83b0671a33 am: 10a48fb557 am: fd84d78b1e
am: b4d92e1362

* commit 'b4d92e1362009637a1d0fb7ee7f96d2812a09202':
  Fix overflow testing in sbrk.

Change-Id: I0e8c70deedb9f43204d306a5fdad22b14703dbe5