Use cffi's new out-of-line mode for faster CPython

[lrowe]

CFFI 1.0 introduced a new out-of-line mode to reduce the overhead when running on CPython.

See:

• http://morepypy.blogspot.com/2015/05/cffi-101-released.html
• https://cffi.readthedocs.org/en/latest/overview.html#out-of-line-example-abi-level-out-of-line

(Wishlist item rather than bug.)

[brentp]

cool. not sure I fully grok this, but faster is good. is it just import times that are improved?

[lrowe]

I had thought it had an effect on runtimes under CPython, but looks like it is just import time. More info here: http://morepypy.blogspot.com/2015/05/cffi-10-beta-1.html

[brentp]

ok. still, seems like ti could be useful, and potentially make the install easier.