mmime: gen_file: remove check for trailing newline for 7bit transfer

RFC2046 5.1.1 specifies that parts without trailing newlines are coded
without problems:

> NOTE:  The CRLF preceding the boundary delimiter line is conceptually
> attached to the boundary so that it is possible to have a part that
> does not end with a CRLF (line break).

This if-statement now also codes empty files correctly.

mmime.c

@@ -246,7 +246,7 @@ gen_file(char *file, char *ct)
 	}
 
 	if (bitlow == 0 && bithigh == 0 &&
-	    maxlinelen <= 78 && content[size-1] == '\n') {
+	    maxlinelen <= 78) {
 		if (!ct)
 			ct = "text/plain";
 		printf("Content-Type: %s\n", ct);