PFR for boost spirit

[denzor200]

Hi, Anton. Recently i created drafted PR with pfr library into fusion.
boostorg/fusion#232
I invite you to participate in the review, if you wish.

[apolukhin]

I've seen it, good job!

I do not maintain the Fusion library and not aware of its internals. My participation won't help :(

BTW, there's a Spirit x3 that does not depend on Fusion, but may also benefit from PFR

[denzor200]

Ok. Thanks for the answer!