The compiler flag -Werror is printed (or not printed) as any other
compiler flag which is part of QEMU_CFLAGS.

Therefore an extra output line for -Werror is redundant and can be removed.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>