Hi,

this small patch fixes the logic in ASan vs SSP interaction to provide 
correct "size" parameter to asan_stack_malloc_[N] routines. With current 
logic, we would have assertion failure in libsanitizer in UAR mode on 
32-bit targets due to wrong granularity of resulting addr + size address.

Regtested via make check RUNTESTFLAGS="--target_board=unix'{-m32,-m64}' 
-j12 on x86_64-unknown-linux-gnu and bootstrapped on 
x86_64-unknown-linux-gnu.

Ok for gcc-4_9-branch?

-Maxim