contrib/xxhash: Add xxhash library

xxhash is a faster non-cryptographic hash.
https://github.com/Cyan4973/xxHash

Release Taken: "xxHash v0.6.2"
--------------

Files added:
  contrib/xxhash/xxhash.c
  contrib/xxhash/xxhash.h
  contrib/xxhash/xxhsum.c

Modifications to source:
------------------------
Following functions and data types got 'GF_' prefix
as below to avoid any form of name collisions in future.

    ---- Functions ----
    GF_XXH_versionNumber
    GF_XXH32
    GF_XXH32_createState
    GF_XXH32_freeState
    GF_XXH32_copyState
    GF_XXH32_reset
    GF_XXH32_update
    GF_XXH32_digest
    GF_XXH32_canonicalFromHash
    GF_XXH32_hashFromCanonical
    GF_XXH64
    GF_XXH64_createState
    GF_XXH64_freeState
    GF_XXH64_copyState
    GF_XXH64_reset
    GF_XXH64_update
    GF_XXH64_digest
    GF_XXH64_canonicalFromHash
    GF_XXH64_hashFromCanonical

    ---- Data Types ----
    GF_XXH_errorcode
    GF_XXH32_state_t*
    GF_XXH32_canonical_t*
    GF_XXH32_hash_t
    GF_XXH64_state_t*
    GF_XXH64_canonical_t*
    GF_XXH64_hash_t

It is linked with libglusterfs.so. A wrapper
funtion is also added for the easy usage in
common-utils.c.

xxhash can be used for the all the usecases where
a faster non-cryptographic hash is required.
gfid to path infra would be using this for now.

NOTE:
----
The gluster coding guidelines check is ignored
as maintaining it further would be difficult.

Updates: #253
Change-Id: Ib143f90d91d4ee99864a10246d5983e92900173b
Signed-off-by: Kotresh HR <khiremat@redhat.com>
Reviewed-on: https://review.gluster.org/17641
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Niels de Vos <ndevos@redhat.com>

0 files changed, 0 insertions, 0 deletions