afs: Add ppc64le changes in osconf.m4 file.

afs: Add ppc64le changes in osconf.m4 file.

If swig package is installed on a ppc64le system, build fails for
"libuafs" while running "shlib-build". "shlib-build" gets executed for
builing ukernel.so and this is triggered if "LIBUAFS_BUILD_PERL" is not
empty. Having "swig" package on system sets "LIBUAFS_BUILD_PERL" to
'LIBUAFS_BUILD_PERL' value. The reason for build failure was inside
"shlib-build", 'linker' was not set (it was empty). 'linker' value is
set based on SHLIB_LINKER, which was not defined in  osconf.m4 if build
system is ppc64le.

To fix this add ppc64le_linux26 case in osconf.m4 file.

Reviewed-on: https://gerrit.openafs.org/13980
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit f9c716fca1becea5a41fbe86535759ef817c924d)

Change-Id: I20a9b58e83166932f9b00370f27a146cf3343ff9
Reviewed-on: https://gerrit.openafs.org/14104
Reviewed-by: Yadavendra Yadav <yadayada@in.ibm.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>