Don't complain when a change fixes a complaint.

The script was telling me:
```
WARNING: use relative pathname instead of absolute in changelog text
\#20: FILE: contrib/cross-build.sh:25:
-# /path/to/openocd/contrib/cross-build.sh <host-triplet>
```

In the change where I changed that line to not refer to an absolute
path.

Change-Id: I1a21af5c36d9aeb01d3e819bfe2b06eb00466467
Signed-off-by: Tim Newsome <tim@sifive.com>

tools/scripts/checkpatch.pl

@@ -1589,7 +1589,7 @@ sub process {
 		}
 
 # Check for absolute kernel paths.
-		if ($tree) {
+		if ($tree && $line =~ /^[^-]/) {
 			while ($line =~ m{(?:^|\s)(/\S*)}g) {
 				my $file = $1;