Fix alignment issues with Jets.

1. Test that reproduces the failure on macos.
2. Move the alignment macros from manual_constructor.h
   to macros.h and rename them to prevent conflicts.
3. The inline array used by FixedArray is now aligned.
4. Jet has been modified to be eigen friendly.

Change-Id: I4563847a767a92156dabab1ab420f0cdddb8ba77