Allow multiple commands per test in test runner (#725)

This CL allows each test to specify more than one command, each of which
will be run, in order, as long as the previous commands all return
errorcode `0`.

For example:
```
;;; EXE: %(command1)s
;;; FLAGS: --foo=1 --stuff
;;; EXE: %(command2)s
;;; FLAGS: --other-things
```

The goal here is to remove many of the test wrapper scripts (e.g.
`test/run-interp`, `test/run-objdump`, etc.) by having their
functionality represented by multiple commands instead, then wrapped
into a `TOOL` definition.

0 files changed, 0 insertions, 0 deletions