malloc and family were not declared with __attribute__((alloc_size)).
This was (sometimes) preventing FORTIFY_SOURCE related functions
from knowing the size of the buffer it's dealing with, inhibiting
FORTIFY_SOURCE protections.
Add __attribute__((alloc_size))
Information about the alloc_size attribute can be found
at http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
Change-Id: Ia2f0a445f0170a7325f69259b5e7fb35a9f14921