Fix compile error with FORTIFY_SOURCE

Nick Kralevich [Thu, 10 Oct 2013 00:24:40 +0000 (17:24 -0700)]
You're gonna have a bad day if you attempt to read 3 bytes
into 1 byte.

Change-Id: Ifc3324c8a13da52b8f447be4f47d0d2649db93bd