autoconf: add AC_CHECK_LINUX_TYPE macro

autoconf: add AC_CHECK_LINUX_TYPE macro

add a macro which looks for a given type in a given linux kernel
header file

Reviewed-on: http://gerrit.openafs.org/8021
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit f87d49cd17fbf6aa9465faadac823ed8d0510a16)

Change-Id: Idc6cc79d9410149f6faeb867f878724beaa30793
Reviewed-on: http://gerrit.openafs.org/8788
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>