Add build support for ppc64le.

* config.guess, config.sub: Update to latest version (2013-11-29).
* m4/libtool.m4: Add patches for ppc64le.
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We don't want to update libtool, thus we use patches supplied by IBM.

Signed-off-by: Werner Koch <wk@gnupg.org>
mpi: fix gcry_mpi_powm for negative base.

* mpi/mpi-pow.c (gcry_mpi_powm) [USE_ALGORITHM_SIMPLE_EXPONENTIATION]:
Fix for the case where BASE is negative.
* tests/mpitests.c (test_powm): Add a test case of (-17)^6 mod 19.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
mpi: add inline assembly for x86-64

* mpi/longlong.h [__x86_64] (add_ssaaaa, sub_ddmmss, umul_ppmm)
(udiv_qrnnd, count_leading_zeros, count_trailing_zeros): New.
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Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>