Convert existing die(..., strerror(errno)) to die_errno()

Change calls to die(..., strerror(errno)) to use the new die_errno().

In the process, also make slight style adjustments: at least state
_something_ about the function that failed (instead of just printing
the pathname), and put paths in single quotes.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fast-export.c

@@ -451,7 +451,7 @@ static void import_marks(char *input_file)
 	char line[512];
 	FILE *f = fopen(input_file, "r");
 	if (!f)
-		die("cannot read %s: %s", input_file, strerror(errno));
+		die_errno("cannot read '%s'", input_file);
 
 	while (fgets(line, sizeof(line), f)) {
 		uint32_t mark;