Add dummy description for GET-INSTALL-PATH

kati takes the first @echo command in a rule and turns it in to a ninja
description that gets pretty-printed.  The GET-INSTALL-PATH is only
@echo commands and is parsed by development/testrunner/runtest.py, so
it fails to parse the pretty-printed first test.

Add a dummy @echo to GET-INSTALL-PATH for kati to use as the
description, so the rest of the @echo commands are left unmodified.

Change-Id: I192fde48b26726a2f6760448f819243bd2f21312