installed-tests: Don't pass WARN_SCANNERFLAGS to warnlib
installed-tests: Don't pass WARN_SCANNERFLAGS to warnlib

This will (typically) pass in --warn-error which is not right
for warnlib, which intentionally has warnings.

endlessm/gjs,endlessm/gjs,endlessm/gjs,endlessm/gjs,endlessm/gjs