checkpatch: emit a warning on file add/move/delete

Whenever files are added, moved, or deleted, the MAINTAINERS file
patterns can be out of sync or outdated.

To try to keep MAINTAINERS more up-to-date, add a one-time warning
whenever a patch does any of those.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -1679,7 +1679,7 @@ sub process {
 
 	my $in_header_lines = $file ? 0 : 1;
 	my $in_commit_log = 0;		#Scanning lines before patch
-
+	my $reported_maintainer_file = 0;
 	my $non_utf8_charset = 0;
 
 	my $last_blank_line = 0;
@@ -2012,6 +2012,17 @@ sub process {
 			      "Please use 12 to 16 chars for the git commit ID like: '${init_char}ommit $id (\"$desc\")'\n" . $herecurr);
 		}
 
+# Check for added, moved or deleted files
+		if (!$reported_maintainer_file && !$in_commit_log &&
+		    ($line =~ /^(?:new|deleted) file mode\s*\d+\s*$/ ||
+		     $line =~ /^rename (?:from|to) [\w\/\.\-]+\s*$/ ||
+		     ($line =~ /\{\s*([\w\/\.\-]*)\s*\=\>\s*([\w\/\.\-]*)\s*\}/ &&
+		      (defined($1) || defined($2))))) {
+			$reported_maintainer_file = 1;
+			WARN("FILE_PATH_CHANGES",
+			     "added, moved or deleted file(s), does MAINTAINERS need updating?\n" . $herecurr);
+		}
+
 # Check for wrappage within a valid hunk of the file
 		if ($realcnt != 0 && $line !~ m{^(?:\+|-| |\\ No newline|$)}) {
 			ERROR("CORRUPTED_PATCH",