Log Message:
gmp: updated to 6.3.0

Changes between GMP version 6.2.* and 6.3.*.

  BUGS FIXED
  * A possible overflow of type int is avoided for mpz_cmp on huge operands.

  * A possible error condition when a malformed file is read with
    mpz_inp_raw is now correctly handled.

  FEATURES
  * New public function mpz_prevprime, companion of the existing
    mpz_nextprime.

  * New documented pointer types mpz_ptr, mpz_srcptr, and similar for
    other GMP types. Refer to the manual for full list and suggested
    usage. These types have been present in gmp.h at least since
    GMP-4.0, but previously not advertised to users.

  * Support for 64-bit Arm under Macos.

  * Support for the loongarch64 CPU family.

  * Support for building with LTO, link-time optimisations.

  SPEEDUPS
  * New special code for base = 2 in mpz_powm reduces the average time
    for the functions that test primality.

  * Speedup for the function mpz_nextprime on large operands.

  * Speedup for multiplications (some sizes only) thanks to new
    internal functions to compute small negacyclic products.

  * Special assembly code for IBM z13 and later "mainframe" CPUs, \ 
resulting in
    a huge speedup.

  * Improved assembly for several 64-bit x86 CPUs, Risc-V, 64-bit Arm.