valgrind testing: extend vg_regtest to emit automake-style .trs/.log files

valgrind testing: extend vg_regtest to emit automake-style .trs/.log files

Extend vg_regtest to produce automake-style log files for each vgtest
case, so that developers and testsuite archiving/analysis tools such
as bunsen can examine passing as well as non-passing test outputs in
detail.  The build-tree test-suite-overall.log file holds all the key
information about tests, especially failures.

Signed-Off-By: Frank Ch. Eigler <fche@redhat.com>