LU-1924 build: configure can not find libgssapi_krb5.so

./configure --enable-gss cannot find on Debian amd64/x86_64
wheezy the file libgssapi_krb5.so although it
exists in the directory /usr/lib/x86_x64-linux-gnu.
Probably some other amd64/x86_64 Linux distributions
are effected as well.

Signed-off-by: Thomas Stibor <thomas@stibor.net>
Change-Id: Ife12e11224db4ef64adbcedb31cc1c07cf1c9b2e
Reviewed-on: http://review.whamcloud.com/4378
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>