checkpatch: treat jenkins as valid email

This is needed to avoid checkpatch barking on already committed patches.

This is the old commit cadd519715 ("checkpatch: treat jenkins as
valid email") re-applied.

Remove the flag BAD_SIGN_OFF, not anymore needed.

Change-Id: I6744f80de982f7934f3a5197ac2df1c29962cbd0
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5120
Tested-by: jenkins

.checkpatch.conf

@@ -30,5 +30,4 @@
 
 # Temporarily lines, to commit checkpatch itself. To be removed!
 --no-tree
---ignore BAD_SIGN_OFF
 --ignore TYPO_SPELLING

tools/scripts/checkpatch.pl

@@ -1403,6 +1403,10 @@ sub parse_email {
 			$address = "";
 			$comment = "";
 		}
+	# OpenOCD specific: Begin: handle jenkins as valid email
+	} elsif ($formatted_email eq "jenkins") {
+			$address = "jenkins";
+	# OpenOCD specific: End
 	}
 
 	# Extract comments from names excluding quoted parts