dir: remove unused test files

dir: remove unused test files

Makefile rules for physio.c and test-salvage.c have been commented out
since the original IBM code import, and were removed in commit
37b4195d603630498664fa0975ea5d5c82f9aa4f 'dtest-20021111' to fix dtest.
However, that commit neglected to remove the source files and other
references to them in Makefile.in

Finish the job by removing the files and references to them.

No functional change is incurred by this commit.

Change-Id: I57527be99cd28a481a86b659d1eb3227af9f1c99
Reviewed-on: https://gerrit.openafs.org/14052
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>