autoconf: Use `uname -p` instead of $HOST_CPU for ctf tools
Currently, we check if the ctf tools are present searching for them in
a few directories. One of these directories (/opt/onbld/bin/$HOST_CPU) looks at
the $HOST_CPU variable, which on x86 can be 'x86_64' or 'i386', but the only
valid directories for the onbld tools are 'i386' and 'sparc'. So instead of
$HOST_CPU, just use $(uname -p), which is only ever 'i386' on x86, and 'sparc'
on sparc.
[adeason@sinenomine.net: reword commit message]
Change-Id: I972cf1cc0dda81f5ee454b14ddbe2830c82c838d
Reviewed-on: https://gerrit.openafs.org/13275
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>