Linux: Macroise kernel function autoconf tests

Linux: Macroise kernel function autoconf tests

We spend a lot of time in autoconf checking to see if kernel
functions are available. Rather than copying and pasting the same
code everytime we do so, create a macro to do function tests, and
use that macro. This results in standardised naming, so change all
of the places that use autoconf results to use the same standardised
names.

Change-Id: I36212e6c28c4b8455f859da1bbf3e456a2aabc07
Reviewed-on: http://gerrit.openafs.org/1849
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>