C++11 has an alignas() specifier, specifying different minimum alignment over
the default (similar to e.g. __attribute__((aligned(N))) or
__attribute__((aligned(alignof(T))))) that can be used in place of our own
home-grown alignment macros and structures. Replace them everywhere.
There is also a standard alignof() to replace MY_ALIGNOF(), but we don't use
MY_ALIGNOF() anywhere except in MY_ALIGN(), so we can just remove the macro.

In PFS, a few PFS_ALIGNED was removed from places where they didn't matter
(the structure was already padded so that it would be alone on a cache line,
so we would only get double-alignment).

Change-Id: I85a987ffff9cea8056f9993b8e08a80f7fc4dc48