[PATCH] checkpatch: do not try to sanity test cover letters

[Paul Gortmaker <paul.gortmaker@windriver.com>]

One possibly common workflow is this:

	git format-patch -o mypatches --cover-letter ^start end
	./scripts/checkpatch.pl mypatches/*

The problem with the above is that checkpatch.pl will try to
parse the cover-letter, and of course complain that it can not
find any unified diff within.

It is pretty safe for us to assume "0000-cover-letter.patch" is
not in fact a patch and simply skip processing of it.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---

[what I know about perl could be written on the back of a postage
 stamp in crayon, so please feel free to reimplement the overall
 concept of this change as you see fit.... ]

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index a3b9782..fc22f4b 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6,6 +6,7 @@
 # Licensed under the terms of the GNU GPL License version 2
 
 use strict;
+use File::Basename;
 
 my $P = $0;
 $P =~ s@.*/@@g;
@@ -382,6 +383,10 @@ for my $filename (@ARGV) {
 		open($FILE, '<', "$filename") ||
 			die "$P: $filename: open failed - $!\n";
 	}
+	if (basename($filename) eq '0000-cover-letter.patch') {
+		print "Skipping cover letter $filename\n";
+		next;
+	}
 	if ($filename eq '-') {
 		$vname = 'Your patch';
 	} else {
-- 
1.7.9.1