GMP used during 3 and a half years to solve MIT's LCS35

[Torbjörn Granlund]

Squaring by means of mpz_mul is about 230 times faster on Ryzen 2700X
using current GMP code compared to the 1999 Pentium 3 with GMP 2.0.2.

For mpz_mod, the former system is about 110 times faster.

The speedup comes from several factors:

1. 64-bit vs 32-bit basic multiply insns gives 3x to 4x
2. Clock speed about 5x
3. Better GMP algorithms and implementations

-- 
Torbjörn
Please encrypt, key id 0xC8601622