more C++ cleanup

Mainly, convert macro CAST(D,v) to cast<D>(S v).

Now that we've got functions passing around U64 by value,
GCC warns bogusly about using registers that aren't enabled.
That doesn't really happen... I think its front-end is confused.

Disabling -Wpsabi stifles that for return values, and passing U64
by const& for arguments.  We can make our 16x4 byte swap function
look a little more normal now too.

And I tidied up the warning supressions a little.  No real reason
to ever re-enable warnings we disable... Transform_inl.h is only
ever included from skcms.cc.

Change-Id: I820f29b35c5fdf6d99773a6b950d9695aa82942f
Reviewed-on: https://skia-review.googlesource.com/144323
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed