scripts/documentation-file-ref-check: exclude false-positives

There are at least two cases where a documentation file was gone
for good, but the text still mentions it:

1) drivers/vhost/vhost.c:
   the reference for Documentation/virtual/lguest/lguest.c is just
   to give credits to the original work that vhost replaced;

2) Documentation/scsi/scsi_mid_low_api.txt:
   It gives credit and mentions the old Documentation/Configure.help
   file that used to be part of Kernel 2.4.x

As we don't want to keep the script to keep pinpoint to those
every time, let's add a logic at the script to allow it to ignore
valid false-positives like the above.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/documentation-file-ref-check

@@ -8,6 +8,14 @@ use warnings;
 use strict;
 use Getopt::Long qw(:config no_auto_abbrev);
 
+# NOTE: only add things here when the file was gone, but the text wants
+# to mention a past documentation file, for example, to give credits for
+# the original work.
+my %false_positives = (
+	"Documentation/scsi/scsi_mid_low_api.txt" => "Documentation/Configure.help",
+	"drivers/vhost/vhost.c" => "Documentation/virtual/lguest/lguest.c",
+);
+
 my $scriptname = $0;
 $scriptname =~ s,.*/([^/]+/),$1,;
 
@@ -122,6 +130,11 @@ while (<IN>) {
 			next if (grep -e, glob("$path/$ref $path/$fulref"));
 		}
 
+		# Discard known false-positives
+		if (defined($false_positives{$f})) {
+			next if ($false_positives{$f} eq $fulref);
+		}
+
 		if ($fix) {
 			if (!($ref =~ m/(scripts|Kconfig|Kbuild)/)) {
 				$broken_ref{$ref}++;