BUG: disable aligned attribute for GCC 4.1

ITK usage is causing internal compilation segfault on the version of
gcc.
BUG: Prevent signed integer overflow in vnl urand_

Use bit shifting instead of power of 2 loop, to prevent signed integer
overflow.

Change-Id: I7369dba8e0d073de4213cfc646e81dda462b9955
Merge topic 'DisableAlignedForGcc41'

2d8c4db BUG: disable aligned attribute for GCC 4.1
Merge topic 'FixVXLSignedIntegerOverflow'

bfef1dd BUG: Prevent signed integer overflow in vnl urand_