Changes to integer-gmp(2)

Changes to integer-gmp:
commit 868b93beb1215a44f5f8251a397bba7fcc0815ad
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Wed Jan 8 23:39:01 2014 +0100

    Manually float out `int2Integer# INT_MINBOUND`

    This avoids allocating this special value over and over again every
    time it's needed, and therefore this addresses #8647.

    Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

commit af2ba9c81cf6a3223ccc74c5aa17de18138fd824
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Wed Jan 8 22:45:13 2014 +0100

    Wrap `gmpz_tdiv_{q,r,qr}_ui` to optimize `quot`/`rem`

    This is useful as `quot`/`rem` are often used with small-int divisors,
    like when computing the digits of an `Integer`. This optimization
    reduces allocations in the following `nofib` benchmarks:

          Program        Size    Allocs   Runtime   Elapsed  TotalMem
       -----------------------------------------------------------------
            power       +0.3%     -0.8%     -1.2%     -1.2%     +0.0%
        primetest       +0.3%     -3.9%      0.07      0.07     +0.0%
              rsa       +0.3%     -4.0%      0.02      0.02     +0.0%
           symalg       +0.2%     -1.4%      0.01      0.01     +0.0%

    This addresses #8647

    Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>