Also test using gmp-d in bigint_benchmark

[nordlow]

Calling dub --build=release

gives

Running bigint_benchmark 
--------------------------------------------
mir speedup = 55.6%
std = 2 secs, 711 ms, 185 μs, and 4 hnsecs
mir = 1 sec, 741 ms, 984 μs, and 3 hnsecs
 ............... 64bit linux ............... 
--------------------------------------------
--------------------------------------------
gmp speedup = 1644.5%
std = 2 secs, 711 ms, 185 μs, and 4 hnsecs
gmp = 155 ms, 410 μs, and 9 hnsecs
 ............... 64bit linux ............... 
--------------------------------------------

, @9il! :)

gmp has 31 years of optimizations in it...

[9il]

That is illegal speed :)

[jmh530]

@9il Might make for a good blog post.