Add strlcpy / strlcat support to FORTIFY_SOURCE. This allows
us to do consistency checks on to ensure we don't overflow buffers
when the compiler is able to tell us the size of the buffer we're
dealing with.
Unlike previous changes, this change DOES NOT use the compiler's
builtin support. Instead, we do everything the compiler would
normally do.
Change-Id: I47c099a911382452eafd711f8e9bfe7c2d0a0d22
