Improve error reporting when a file given on the command line

cannot be opened:
* Mention the filename.
* Report the errno for the file itself, not the one with .gz appended.

1 files changed, 2 insertions, 2 deletions

diff --git a/main.c b/main.c
index 1f738439..36eb565d 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.317 2019/01/10 06:29:00 schwarze Exp $ */
+/*	$Id: main.c,v 1.318 2019/01/11 17:04:44 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2012, 2014-2019 Ingo Schwarze <schwarze@openbsd.org>
@@ -561,7 +561,7 @@ main(int argc, char *argv[])
 			}
 		} else
 			mandoc_msg(MANDOCERR_FILE, 0, 0,
-			    "%s", strerror(errno));
+			    "%s: %s", thisarg, strerror(errno));
 
 		if (curp.wstop && mandoc_msg_getrc() != MANDOCLEVEL_OK)
 			break;