swc-installation-test-2.py: Add CommandDependency.stdin
swc-installation-test-2.py: Add CommandDependency.stdin

I'm about to implement a version check for 'make' where I want to pass
a test Makefile in via stdin.

selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest