In some cases of overriding or resetting locations, we might retain
discriminator info from earlier locations, when we should take
discriminator information from the overriding location or reset it.

for  gcc/ChangeLog

	* final.c (compute_discriminator): Declare.  Renamed from...
	(maybe_set_discriminator): ... this.  Set and return a local.
	(override_discriminator): New.
	(final_scan_insn_1): Set it.
	(notice_source_line): Adjust.  Always set discriminator.

From-SVN: r266349