Added tests for finding crash bug conditions.
While owner has a record:
  - 13-drop-table: drop table
  - 14-alter-table: alter table

While owner waits a record:
  - 13-drop-table-while-waiting: drop table

Needs review for 13-drop-table-while-waiting.t before making:
  - 14-alter-table-while-waiting
  - 15-delete-while-waiting

Signed-off-by: Sho Nakatani <lay.sakura@gmail.com>
Fixed 13-drop-table-while-waiting.t:
Now child process does not call any of Test::More functions.
Rather, its exit status is checked by parent.
Signed-off-by: Sho Nakatani <lay.sakura@gmail.com>
Fix: easy miss when using __LINE__
Signed-off-by: Sho Nakatani <lay.sakura@gmail.com>
Merge pull request #3 from laysakura/crash-test

Added tests for finding crash bug conditions.