autoconf: add test for typedef'd structs

autoconf: add test for typedef'd structs

AC_CHECK_LINUX_STRUCT does not work for structs which are typedef'd.
The gcc will complain with "error: storage size of ‘_test’ isn’t known"
and fail the test.
Thus the new test-macro AC_CHECK_LINUX_TYPED_STRUCT.

Reviewed-on: http://gerrit.openafs.org/4718
Reviewed-by: Christof Hanke <christof.hanke@rzg.mpg.de>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit baf7656f666e0d47047c545561345e7803b8a141)

Change-Id: I7feca884d7796ccd3a490d6b81e745c644d9c8f1
Reviewed-on: http://gerrit.openafs.org/4725
Reviewed-by: Christof Hanke <christof.hanke@rzg.mpg.de>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>