Log Message:
gmp: updated to 6.2.0

Changes between GMP version 6.1.* and 6.2.0

BUGS FIXED
* gmp_snprintf now correctly reports an error (returns -1) when snprintf
  does.
* Conversion to double is now more robust even if the configuration process
  does not recognize the float format.
* mpz_powm could return a not completely normalised value, when the
  exponent was 1 and the base < 0.
* mpf_set_str could create invalid mpf_t variables for input strings with
  many leading zeros.

FEATURES
* New C++ functions factorial, primorial and fibonacci for mpz_class.
* Functions to detect primality now substitute the first 24 Miller-Rabin
  iterations with the BPSW test.
* Mini-GMP: new functions mpz_2fac_ui and mpz_mfac_uiui.
* Mini-GMP: mpz_sizeinbase, mpz_get_str, and mpz_set_str now support bases up
  to 62.
* Mini-GMP: added support for the mpq_t layer.
* MIPS r6 cores are now supported.

SPEEDUPS
* Major speedup for AMD Ryzen and Epyc thanks to an extensive set of assembly
  code.
* Major speedup for IBM POWER9 thanks to assembly code making use of new madd
  instruction.
* Speedup for 64-bit ARM CPUs thanks to new/improved assembly code.
* The n-over-k function mpz_bin_ui has been reimplemented for great speedups
  for large operands.
* Speedup for the worst case of mpz_perfect_power_p.
* Speedup for gcd for small and medium size operands.
* Speedup for really huge multiplies thanks to much larger FFT tables.

MISC
* Internal representation of the mpz_t variables now supports lazy
  allocation; memory is allocated only when a value is stored.
* Small improvements and better coverage for the test suite.
* The tune/speed program can measure some more functions.
* The low-level function mpn_mul no longer diverts to mpn_sqr, users should
  call mpn_sqr directly when applicable.
* New installed files gmp.pc and gmpxx.pc, for use with pkg-config.