traces in Valgrind (broken libc6-dbg).
Installing libc6-dbg on Debian will still provide proper bactraces, even
without setting LD_LIBRARY_PATH explicitly.


mysql-test/lib/mtr_io.pl:
  Do not link /usr/lib/debug/* on Debian <=3.1, as it causes broken stack
  traces in Valgrind.
mysql-test/mysql-test-run.pl:
  Do not link /usr/lib/debug/* on Debian <=3.1, as it causes broken stack
  traces in Valgrind.