test: fix windows build

Broken by e7173dfdfd1c74b1d301da9b6f295ef99b9cc11c

Fix by simply disabling the relevant tests.

* bug248 and bug345 require errchk, but we can't
  rely on perl being available.
* bug369 is disabled anyway.

Change-Id: Idf73ebccb066943e3fe17c2f662b37238ec74dfe
Reviewed-on: https://go-review.googlesource.com/2052
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>