remove trailing LF in die() messages

LF at the end of format strings given to die() is redundant because
die already adds one on its own.

Signed-off-by: Alexander Potashev <aspotashev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin-cat-file.c b/builtin-cat-file.c
index 30d00a6..8fad19d 100644
--- a/builtin-cat-file.c
+++ b/builtin-cat-file.c
@@ -137,7 +137,7 @@
 		break;
 
 	default:
-		die("git cat-file: unknown option: %s\n", exp_type);
+		die("git cat-file: unknown option: %s", exp_type);
 	}
 
 	if (!buf)