With buffered warnings, most warnings *must* be issued on every pass,
so ERR_PASS1 is simply wrong in most cases.
ERR_PASS1 now means "force this warning to be output even in
pass_first(). This is to be used for the case where the warning is
only executed in pass_first() code; this is highly discouraged as it
means the warnings will not appear in the list file and subsequent
passes may make the warning suddenly vanish.
ERR_PASS2 just as before suppresses an error or warning unless we are
in pass_final().
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>