MEDIUM: tools: read_line_to_trash() handle empty files without \n

fgets() returns NULL when EOF is reached before newline, handle
that as a success for consistency, current behaviour is arguably a bug,
the API of fgets() is pretty weird after all so someone probably forgot.

src/tools.c

@@ -6906,6 +6906,9 @@ ssize_t read_line_to_trash(const char *path_fmt, ...)
 			trash.data--;
 		trash.area[trash.data] = 0;
 		ret = trash.data; // success
+	} else if (feof(file)) {
+		/* empty file is allowed */
+		ret = 0;
 	}
 
 	fclose(file);