open to "|-" and "-|" are unsupported on Windows (see `perldoc
perlport'), so don't do that.
Rather than parsing the output of make to decide if a config test is
skipped, use a looser definition: it is skipped if qmake and make both
succeed, but no binary is created.
Change-Id: Idab7266888e9c934aa7b5c1c6ac5930439681107
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>